I don't know if I would call a $10 buy in "serious" But I think there is a balance to be had between completely farting around and playing poker.
I have played nickel-ante poker and it was fun, but I don't know if it really captures the flavor of poker. When I played nickel-ante, it was almost impossible to bluff because people would call on just about anything because the amount of money involved was so trivial. Bluffing is an important part of the game, IMHO.
$10 seemed like the sweet spot to me. With $10, the pots are decent enough to represent "real" money, but not high enough to where you are really sweating it if you lose.