Would you prefer that we be a bit more hardcore about subscribing sequences, and a bit more explicit that people should read them?

In short, no. See my other comment for details. I think the barriers to entry are high enough, and raising them further filters out people we might want.

Or maybe we should have little markers next to people's names "this guy has read everything"?

This introduces status problems, it's impossible (or at least inefficient) to enforce well.

Or maybe we should do nothing because all moves are bad?

I won't claim that the current design we've located in LessWrongspace is the most optimal, but I'm quite happy with it, and I don't see any way to immediately improve it in the regard you want.

Actually, I'll take that back. I would like to see the community encourage the use of tags a lot more. I think if everyone was very dedicated in trying to use the tagging system it might help the problem you're referring to. But in some way, I think those tags also need to be incorporated into titles of discussion posts. I really like the custom of using [META] or [LINK] in the title, and I'd like to see that expand.

Maybe a more loosely affilated site that has the strict standard instead of just a "non-noobs" section?

Again no, really for the same reasons as above.