So this is one of these 'its a feature not a bug' type of things? I hate it when you can't see what's happening under the hood, also addresses are useful for keeping track of what my one mining pool sent me, what my other pool sent me... They're like folders and multibit is forcing you to adopt their 'wallets only for organization' paradigm. I remember clearly that once upon a time you could see the individual address balance in MultiBit, but rolling back to an older version probably isn't smart for safety reasons.
The addresses that you have given to people you can label to see when you've been paid by them.
Yes, you can label the wallet. Which means that if 20 people pay me rent every month, I have to have at least 20 wallets.
You can review incoming transactions to see who paid you what, and to what address.
There is no concept of per-address balance that is reasonable to present to users.
I receive a 1 BTC payment to an address I gave you, that address's balance is 1 BTC. I send a 0.01 payment to someone else, that address's balance is now 0. It should remain 0 and should not be reused.
Wait, what? Maybe
http://we.lovebitco.in/how-bitcoin-works/transactions/ will give you some insight into the inner workings.
There is a concept of "accounts" in Bitcoin code that may be used by programmers, but it is not exposed or used by the wallet interface.