No issues with export wallets/private keys. I share gmaxwell's concerns about making it easy to shoot yourself in the foot, but most of us are grown-ups and if you're talking using the RPC interface there are already plenty of ways to shoot your feet.
Remove private key I had issues with, because if you're using the 'accounts' feature then removing keypairs from a wallet (and their associated transactions) does unpredictable things to account balances. At the very least, I think it should tell you what effects it had. Maybe a JSON result that tells you how account balances changed, e.g. { "" : 1, "John's Wallet" : 6.2, etc.}. That way, if it had an unexpected effects you would know to restore the wallet from backup.
And it seems like 'sweep private key' and 'merge wallets' is really the functionality most people want, not import private key/wallet keys. The only issue I have with them is they are slow because of the rescanning of the block chain, and they may not work or may not be secure if you don't happen to have the whole block chain downloaded.