I agree with you in one sense that yeah you average street trials is just natural style but using walls and rails. However I'm not so sure that street style is dead I just think it's moved onto other bikes. You said yourself few people ride 24's but also think of the amount of people who ride BMX or 26inch jump hard tails for street. I think really trials has grown away from the street style in general but there are other bikes now which you can use to jump stair sets, manual walls and mess around in skate parks. I think the U.S scene is ahead of us in this sense with riders such as Aaron Chase and Dylan Tremblay (both awesome riders of technical street). It's just my opinion but why not have one bike set up for pure trials(screeching brakes long frame) and one for pure street (BMX, Single speed hardtail with sus).