I would be careful in using the terminology "JavaScript-free".
What you mean by that is obviously that the user of the library doesn't need to write JavaScript to use your library. But when it comes to web design, here is actually such a thing as writing functionality that works without JavaScript enabled in the browser (often called graceful degradation).
Normally I would not fuss over such a detail, but since literal JavaScript-free/optional functionality is an actual topic in webdesign, I would encourage you to pick a better phrase for your library (which runs and requires JavaScript), as to avoid confusion that the library itself would work without JavaScript enabled.
I like the phrase "Declarative AJAX", although it might be a bit on the technical side of your target audience.
When I built the library it was partially out of frustration at how hard much code it was to build simple AJAX functionality out in jQuery, ember, etc. and that's reflected in the original hook, but, upon reflection, it can come across as both negative and confusing.
Because you asked - I think the main thing that impeded my ability to quickly understand Intercooler.js's functionality was the excessive use of jargon. I don't see why you even mention 'PVC', 'declarative' [1], 'REST-ful', 'HTML5-style bindings' [2], 'richer UX', etc. It all has meaning, but it hurts communicating what is really incredible about what you've created here: simplicity. The 'richer UX' also gets off track as if this is introducing AJAX to people who have never seen AJAX before. Certainly a legitimate audience, but it doesn't jive whatsoever with the developer target audience clearly visible in the rest of the material.
My suggestion would be "Simple HTML-based AJAX", and then an introductory value proposition statement below that that references the interoperability [3] of the framework and restates the main hook but with a bit more detail (HTML attributes instead of just 'HTML' etc. Maybe make the AngularJS analogy as well, that helped my understanding a lot).
I also really like the demo on the landing page. Very clever putting a link to the next page there.
[1] Not really jargon, but in my opinion implies something more idealistic like Prolog than the pragmatic simplicity you have here.
[2] I don't even know what this one refers to.
[3] Referred to as 'scalable' in your current landing page. The fact that this is a library and not a framework is really something I like seeing - far easier to start using in an instant.
What you mean by that is obviously that the user of the library doesn't need to write JavaScript to use your library. But when it comes to web design, here is actually such a thing as writing functionality that works without JavaScript enabled in the browser (often called graceful degradation).
Normally I would not fuss over such a detail, but since literal JavaScript-free/optional functionality is an actual topic in webdesign, I would encourage you to pick a better phrase for your library (which runs and requires JavaScript), as to avoid confusion that the library itself would work without JavaScript enabled.
I like the phrase "Declarative AJAX", although it might be a bit on the technical side of your target audience.