I think the importance of the front page is overblown. But I think a larger problem is that if you require multiple people to approve a post for the front page, the front page will become *very* static. It's better (IMHO) to have material that doesn't deserve to be there for a short time than better material that's there too long.
And as far as monks approving thier own posts for the front page? I'm sure it happens very occasionally. Often enough to warrant vrooms investment in time to fix it? I doubt it.