You have actually seen more craft beers than you'd realize would qualify for the definition of "lite" if anyone cared to call them that, but they have less reason to call them that because the term arose in the context of the macro lager mono-culture of decades past and hasn't been particularly relevant outside of that context.
First you have to ask yourself what exactly a light beer is and where it came from.
It's different than its big brothers but it's also partially a branding/marketing device. This creature as we usually know it is a lower calorie, lower ABV, lower taste version of a grocery store macro lager that we already know. In reality, it's probably more accurate to say it's just a different beer with those lighter qualities that rides the coattails of the existing brand for the sake of efficiency. It's easy to put out Bud Light successfully when Bud already exists, for example, rather than to make it start from scratch building up brand value in consumers' minds, even if it winds up branching off and continues to evolve into a wholly different identity.
How similar they actually are in terms of ingredients, process, and resulting flavor is probably arbitrary. Maybe those guys could comment.
But think back to the old Miller Lite ads from the 80s, where sports celebrities would divide into teams and argue back and forth about whether Miller Lite "tastes great" or is "less filling". The answer from Miller of course was "both!"
So the idea of these beers in the context of the diet-conscious 70s and 80s was to deviate from the norm of the mono-lager that hovered around 4.8 to 5% and carve out a new category, whether because you want to watch your calories or because you want to be able to drink more without getting as filled up.
And that category pretty much existed only relative to another category, which for most people in the USA back then was the only category, effectively.
And on that note, when you look at the description of Sam Adams Light, which is the only "lite" craft I can think of, they go out of their way to say "Sam Adams Light is not just a lighter version of our Samuel Adams Boston Lager but rather the culmination of over two years of tireless research and brewing trials that proved to be worth the wait." So they're saying it's its own thing, a different beer that happens to have these lighter characteristics comparable to the big macro lites.
It's 4.3% ABV by the way, just a whisker higher than Bud Light and Miller Lite.
But from there, we can recognize that there are also other craft beers out there with similarly lighter characteristics that aren't classed or branded or pitched as being in this light/lite category as we know it. And there are old world styles that have been lower ABV all along. So we might ask, "What's in a name? A beer by any other name would be as light."
Session beers are all the rage these days, most notably session IPAs, and brewers are finding ways to pack more and more flavor into beers that are lower and lower ABV.
The pitch is "you can enjoy more beers with your bros in a session and not get all fucked up as quickly." That's not quite diet consciousness but it can double as that if you want it to, though the ABV range of "session" seems to keep expanding. There are even a few "table" beers and "small" beers out there that are super low ABV, much lower than these session IPAs, though I can't verify whether the flavor holds up since I haven't had them.
But take Bud Light and Miller Lite – if any beers out there typify the light/lite category, it's those two and they clock in at about 4.2% ABV. By comparison Bud heavy is 5%, at least in the USA.
So let's use those as our benchmarks.
- Firestone Walker Easy Jack is a session IPA that weighs in at 4.5% ABV, as many of these newer session IPAs do. Not quite Bud Light strength but not quite Bud heavy either. So that's sort of "lite". Certainly lite-er.
- Stone's Go To IPA is 4.5% and their now-retired Levitation, which wasn't described as an IPA of any kind but was kind of an early example anyway, was 4.4%.
- Dogfish Head Festina Peche is a Berliner Weisse at 4.5%. The lower ABV in this case is typical of the style more so than a deliberate effort to lower the ABV of an otherwise boozier style.
Same goes for Bells Oarsman, a Berliner Weisse at 4%. In fact, look at the Berliner Weisse style page on BeerAdvocate. Check the ABV column. Some of them are higher than Festina Peche, but most are below 4.5%, even below 4%. De Garde has one at 2.3%. Cigar City, if this can be believed, did one at 1%. By comparison to those, Bud Light is for people trying to cultivate mass.
Victory Donnybrook Stout is 3.7%
- Anchor Small Beer is 3.3%.
- Jester King Commercial Suicide is a 2.9% "farmhouse mild" ale inspired in part by the traditional English mild style that's already low ABV.
- Jester King Le Petit Prince is a farmhouse table beer at 2.8% ABV.
As for calories, ABV isn't an exact determinant of a beer's load in that respect, but it's close enough to get a loose idea.
There are other things like residual sugars, which vary from beer to beer and contribute different amounts of calories, but the alcohol provides most of the calories. Brewers could tell you better since they deal in concepts like original gravity and final gravity.
So you can ask why we haven't seen more craft "light" beer if you want to, but if you do, recognize what it is you're asking about.
There are already a fair amount of beers out there that either approach, meet, or beat the "lightness" of the Bud Lights and Miller Lites and whatnot, but are so much more flavorful, but they just aren't classed or called or pitched as light beers. That's because the very concept of a light beer as we know it is partly a branding/marketing device and is often defined relative to other product offerings by the same companies.
Jester King Le Petit Prince is substantially lighter than Bud Light but does not care about that or about any other beer in the Jester King portfolio. It's that ABV because that's just part of what comes with that style. In fact, traditional table beer back across the water was often even lower than that.
With all of that said, you could accurately brand and market any of the above beers as "light" and maybe reap some of the enduring sales benefits that come from people's perception of what light beer means. Maybe that's actually what you're asking. But at that point I'd defer to ElGringoAlto's answer in this thread. Most of us craft fans have not wanted or cared about light beer ever since we moved away from macros for reasons of flavor.
I don't care too much about ABV or calories myself – I want flavor and complexity and other nice things however you can get them to me.
But maybe as the macro and craft worlds and audiences continue to converge, we actually will see more craft beers pitched as "lite". If somebody's goal when they go to the store is to buy beer that is specifically lower calorie, maybe it makes sense to market to them with a word they already recognize and instantly know the definition of. They may have no clue that berliner weisses are typically lower ABV/calorie, but they know "light". And they may not know tha ABV scales similarly to calories but, again, they know "light".
So that might be a really effective way to grab the business of someone who likes craft but wants lower cal, or this category of people who don't know anything about craft and are still fine with macro but want to experiment while keeping it light.
Guess we'll see.