The interwebs, they are aboil!
Before we all nominate as Shark or Jet, I'd like to take this opportunity to point out the common ground: both the "JS required" ("requiredJS"?) and "PE or Bust" crews implicitly agree that HTML+CSS isn't cutting it.
PE acknowledges this by treating HTML as scaffold to build the real meaning on top of. RequiredJS brings its own scaffolding. Apart from that, the approaches are largely indistinguishable.
In ways large and small, the declarative duo have let down application developers. It's not possible to stretch the limited vocabularies they provide to cover enough of the relationships between data, input, and desired end states that define application construction. You can argue that they never were, but I don't think that's essentially true. Progressive Enhancement, for a time, might have gotten you everywhere you wanted to be. What's different now is that more of us want to be places that HTML+CSS are unwilling or incapable of taking us.
The HTML data model is a shambles, the relationship between data, view, and controller (and yes, browsers have all of those things for every input element) is opaque to the point of shamanism: if I poke this attribute this way, it does a thing! Do not ask why, for there is no why. At the macro scale, HTML isn't growing any of the "this is related to that, and here's how" that the humble
<a href="..."> provided; particularly not about how our data relates to its display. Why, in 2013, isn't there a (mostly) declarative way to populate a table from JSON? Or CSV? Or XML? It's just not on the agenda.
And CSS...it's so painful and sad that mentioning it feels like rubbing salt in a wound that just refuses to heal.
Into these gaps, both PE and requiredJS inject large amounts of JS, filling the yawning chasm of capability with...well...something. It can be done poorly. And it can be done well. But for most sites, widgets, apps, and services the reality is that it must be done.
Despite it all, I'm an optimist (at least about this) because I see a path that explains our past success with declarative forms and provides a way for them to recapture some of their shine.
Today, the gap between "what the built-in-stuff can do" and "what I need to make my app go" is so vast at the high-end that it's entirely reasonable for folks like Tom to simply part ways with the built-ins. If your app is made of things that HTML doesn't have, why bother? At the more-content-than-app end, we're still missing ways to markup things that microformats and schema.org have given authors for years: places, people, events, products, organizations, etc. But HTML can still be stretched very nearly that far, so long as the rest of the document is something that HTML "can do".
What's missing here is a process for evolving HTML more quickly in response to evidence that it's missing essential features. To the extent that I cringe at today's requiredJS sites and apps, it's not because things don't work with JS turned off (honestly, I don't care...JS is the very lowest level of the platform...of course turning it off would break things), but because stuffing the entire definition of an application into a giant JS string deprives our ecosystem of evidence that markup could do it. It's not hard to imagine declarative forms for a lot of what's in Ember. Sure, you'll plumb quite a bit through JS when something isn't built into the framework or easily configured, but that's no different than where the rest of the web is.
Web Components are poised to bridge this gap. No, they don't "work" when JS is disabled, but it's still possible to hang styles off of declarative forms that are part of a document up-front. Indeed, they're the ultimate in progressive enhancement.
I'd be lying if I were to claim that bringing the sexy back to markup wasn't part of the plan for Web Components the whole time. Dimitri's "you're crazy" look still haunts me when I recall outlining the vision for bringing peace to the HTML vs. JS rift by explaining how HTML parsing works in in terms of JS. It has been a dream of mine that our tools would uncover (enabling understanding of) what's so commonly needed that HTML should include it in the next iteration. In short, to enable direct evolution. To do science, not fumbling alchemy.
It's key to understand is that "PE or Bust" vs. "requiredJS" isn't a battle anyone can win today. The platform needs to give us a way to express ourselves even when it hasn't been prescient of our needs -- which, of course, it can't be all the time. Until now, there hasn't been that outgas, so of course we reach out and use the turing-complete language at our finger tips to go re-build what we must to get what we want.
The developer economics will be stacked that way until Web Components are the norm. Call it PE++ (or something less clunky, if you must), but the war is about to be over. PE vs. requiredJS will simply cease to be an interesting discussion.
Can't wait for that day.