There are some absolutely amazing HTML5 / WebGL things out there; I'm just not sure you've seen them. It's true that browser incompatibility is an issue, but say you're ONLY targeting Chrome desktops, which still has a bigger user base than most consoles--if you're doing it right you're getting hardware accelerated graphics and the performance is pretty great. Have you seen cloudparty.com? It has multiplayer in-world building, skeletal animation, particles, full screen effects... the works, and the performance is definitely up to snuff. Observe tons of realtime screencasts here: http://www.youtube.com/user/CloudPartyInc
I think that the problem is that WebGL is young and there are LOTS of ways to shoot yourself in the foot perf-wise. Only a few teams have really figured it out and the rest are making the tech look bad. But the performance is there if you're an experience graphics programmer and you know your way around JS wackiness.
After going through a few of those examples, the performance really isn't that good. For example, in Chrome my computer struggles to run "The Isle of Yosemite" in 1650x1050 at 30fps when looking at a fair bit of geometry. Yet I can easily play Battlefield 3 or Natural Selection 2 at 30fps, and the gulf in image quality, how much is in a given scene, and how much game logic there is is enormous.
Thus far, HTML5 games seem more like a replacement for basic 3D flash games more than anything. Whether that will change at some point in the future I don't know, but at this point I have not really been wowed by anything.
I think that the problem is that WebGL is young and there are LOTS of ways to shoot yourself in the foot perf-wise. Only a few teams have really figured it out and the rest are making the tech look bad. But the performance is there if you're an experience graphics programmer and you know your way around JS wackiness.