The beaches are a mixed bag, IMO. Atlantic Beach is the most unique and "post card"-ish.
PVB does have a suburbia vibe, but there's no doubt about it: it's nice. Some really beautiful homes, and PV Boulevard is a beaut.
Jax Beach deserves a lot of the trash talk, but I think they've progressed in leaps and bounds from what it was 5-15 years ago. At least where my dad lives (34th, one block from ocean), the houses going up are unique, interesting, and make for great neighborhood vibes. I think it just depends where you are in Jax Beach. The area around JTB (30th-36th avenues, I think), architecturally, is getting nicer. The rest of Jax Beach doesn't have a 'wow' factor, but it's getting better in terms of places to eat, things to do, places to shop, etc.
And yeah, I bet if you polled residents of the Jacksonville Beaches, 99/100 wouldn't give a damn about walkability. Most of the people I know who live at the beach walk within a 4-block radius of their house, at sunset, with a glass of wine. That, or they're walking on the beach closest to their home. Everything else requires a car, and I think not only have they accepted that, but they're OK with that. To each his/her own.