Hmm, I only scan read this thread, but as bitcoinj based wallets are one of the primary guilty parties in address re-use I'll just pop in to give my view:

People already have the right incentives to not re-use coins (privacy). SPV wallets suck at it today because I chose backup safety over privacy, but BIP32 let's us have our cake and eat it in that regard and it's now being implemented. So at some point SPV wallets will update and addresses will start automatically changing, users won't have to do anything. I'm figuring out ways existing wallets can be upgraded in place.

Punishing address re-use NOW, when many users who are doing it don't have any good way to stop, is just attempting to pressure volunteer wallet developers through their userbase. That's not cool. I already spend a lot of my spare time at evenings and weekends fixing bugs and keeping up with the Bitcoin protocol (20% only gets you so far and can't always be taken). Being "forced" to do it by punishing my users would be quite upsetting, especially as it's coming anyway and Bitcoin-Qt itself doesn't even implement BIP32 properly yet (AFAIK only Electrum has done this?).