One of the hardest problems is like Velojet says you need an authoritative server to prevent cheating. However C2's architecture does not lend itself easily to that - even with a good WebSocket plugin (and even assuming it had UDP support) you might have to hand-code a server for your game, and multiplayer programming is pretty tricky on top of that.
Given we have a community of people who are trying to avoid traditional programming, do you think that would still be useful at all? If you had to code a serverside? If so, we could still make some of the clientside plugins (like WebSocket) to provide official support for that. However we wouldn't be able to help much with writing serversides, it would probably be too complicated to write any kind of simple step-by-step tutorial for it.
We'll always have to hand code our own servers, and people who cannot grasp code aren't able to grasp the requirements behind multiplayer (servers, databases, caching, network issues, clustering, dead reckoning, cheat prevention, etc). There isn't any tool in the market able to simplify server coding as much as construct simplifies game development, and besides a "MMORPG MAKER", I don't think there is demand for one such tool.
That being said, I'd love to see an official multiplayer plugin from scirra, though HTML5 isn't ready for it yet - for now it's best that those plugins be made by the community (we're doing great with what we've got, I've been able to implement multiplayer in everything that didn't require a real time element).