I can't help but think that people who want to replace HTML+CSS+JS haven't written a widely used web application before, because the idea seems so absurdly impractical and would become such an incredible time sink.
Most of lisps problems these days stem from social issues and logistical issues. The core tech is excruciatingly sound, and the language itself is great.
To someone out in the startup circles, it almost seems like Lisp and Scheme focus more on being a standard than being a pragmatic and global platform. While noble, this is not the path to massive popularity. Some people might be okay with that, but it seems to me like you could serve both goals and end up with an overall better product.
You do get that this is exactly what Lisp hackers who build web apps do?
HTML, on the other hand, is easy to abstract. I'm glad I did it in Weblocks, it saves me an enormous amount of time. ASP.NET uses this strategy (use the DataGrid control for a while, and then try coding without it).
JS is somewhere in the middle.