There aren't many users with rep over 3000. So, IMO, the "vote to close" feature (on the main forum) may not work properly. Consider reducing the amount of rep required.
This has been brought up many times on several SE sites, including Meta SO. It's a valid point, and the answer seems to always boil down to getting users more rep instead.
If we keep voting on questions and answers, these low-rep users will be able to vote to close soon enough. Closing a question requires judgment, and the only way we can assure users have that is to rely on their rep. Until we can get to that point, we encourage users to flag questions they think need to be closed and the moderation team will review the problem.
Also - and I think this is a more important reason - if we were to do this, we'd essentially have three reputation setups, one for beta sites, one for full sites, and one for intermediary sites that have just graduated. This will have the effect of placing those sites in a new, second-class bucket.
However, in the end, this is a request for a change to core functionality that'd have network-wide effects. Meta Stack Overflow can handle this, but not a per-site meta.