Only at bitcointroll forums could giving money back to the chain be considered theft. Stay with your non interest bitcoin and see how far you go, SolidCoin is becoming a real economic force by allowing a variety of new services to be built on top its protocol.
Personally I think it's an awesome idea that reduces the effects of spam, essentially a self cleansing p2p network, while also giving funds back to the network in a fair manner.
People now have a financial incentive to be
less anonymous. Way to go!
Yes because tracking the change in Bitcoin is so hard! Having a single address is just as secure as multiple if multiple aren't wisely used (like in Bitcoin).
In the long term a p2p network without self cleansing is going to die, we already see lots of people complaining about Bitcoin's resource usage and performance and it is still in its infancy. If people want to use multiple accounts they can, the average user doesn't care much about it however, so only the paranoid should pay for it rather than everyone.
Lets not burden the network with the tin foil wearing lolcat posters shall we?