There's about 3 LFS's I frequent around here. PetSmart, a local chain, and just a single free-standing local store. PetSmart sells some plants, only notable one being amazon swords. About 90% I've never heard of, or people insist aren't aquatic plants. The local chain did have a plant tank with some wisteria and vals, but most of it was a decaying mess. They did have some anubias, but at over $15 a plant for a plant that's nearly croaked, it's not worth it either. The single local store doesn't have any sign of plants. For this reason, I tend to think LFS's selling aquatic plants simply isn't profitable.
If there was an LFS selling plants like HC, riccia, vals, crypts, hygro etc. at reasonable prices, I'd probably buy there in a heartbeat. Mail order hobbyists and my local fish club is about the only 2 ways I acquire plants. Even the local fish club is highly cichlid-oriented, and I can hear an audible groan whenever someone mentions plants.
I just don't think there's enough interested in aquatic plants for it to be commercially profitable at a brick and mortar store. As people have been said before, it's not widely considered a hobby where you invest much money in. When people ask me how much my 3 tanks in the basement cost me (10, 20, 29), and I tell them it's getting pretty close to the $1000 mark, they start choking. On the flip side though, I've seen my friends blow well over $1000 on guitars, or car modifications, or video games. What I think is stupid to spend money on, some people think there's no better way to spend it, and vice versa. When they scoff at my $250 CO2 system, I get to scoff at their $250 thing to make their guitar sound different.
With that said, planted tanks are more of a hobby than a showcase thing. It's difficult to setup a planted tank without investing effort and money, unless you buy a whole fleet of ADA products, copy an Amano scape, and just dose based on package directions. Even then, when something goes amiss, you'll wish you had done your research.
Personally I think it's an awesome hobby. It's a great mix of science and art, and while I generally lurk on the science side, the art is definitely there. My aquascapes have gone from blue-gravel anacahris atrocities to starting to see some semblance of beauty. With each re-design I get a little better. I'm also hoping in the coming year to NOT neglect my tanks so I don't end up killing the expensive plants.