My only concern is that they are so long.

If there was a passing lane that ended in one kilometer and you tried to pass the road train and ran out of passing lane, you'd be pretty screwed.

I don't know about that one, how much do you really need to know?

There is next to no XML in anything I've ever written, most communication between services is done in JSON - I doubt there would be much XML in Wave either.

If you've got a good ORM back-end, there shouldn't be any need to hand-code SQL for most server-side applications.

That whittles it down to four, and I think it's a small price to pay for the advantages of web-based applications (on which I need not expand).

Also, server-side JavaScript is really coming along and will knock out the requirement for one of those skills.