tacitus59: The first most universal problem is they are very close to being a monopoly and at some point they might start behaving like a monopoly; with steamworks being used for by others for new releases such as FO:New Vegas, we are one step closer
Only in the sense that Securom (including pre-activation model) and Gamespy Arcade had "monopolies". There is still retail, and Steam doesn't actually have any input on the games that use said framework (that was kind of the point of how Steamworks was released).
The second is a general issue with account based digital distribution - they can ban your account and you are totally hosed. There are bascially no consumer protections against this arbitraty behaviour. Generally you can't transfer account to another person (and that is true of all account based download serviced that I know of). Now selling accounts is bad; but if I die my account technically goes bye-bye as well, because of the non-transferable nature of these products.
Consumer protection against arbitrary banning is common sense. If Steam ACTUALLY arbitrarily banned people, people wouldn't use it. I have had a Steam account since the early betas (used it to get a free Counterstrike to play with my friends) and haven't been arbitrarily banned yet, so I am not too concerned.
As for the rest: I believe that is the point of licensed software, but I don't have enough legal knowledge to debate it.
You also can't give a disk to your buddy to play once you have finished playing it; once its been registered on steam works.
*cough* Don't copy that floppy *cough*. :p
Seriously though, I am pretty sure that was intentional.
If steam or another service goes down or there is a rights fight they can cut off a game quickly with no reimbursal. GOG is the only major exception, they can prevent access to redownloading, but if you have a back-up copy your OK because of no DRM.
You can actually do the same with Steam. You just might need to use a crack to play it, which is actually true of a lot of retail games with activation-based DRM models anyway.
Also, my experience is that they use the same basic approach GoG does. The Alien Shooter guy got angry at Strategy First and tried to pull Alien Shooter 2 and replace it with AS: Reloaded. So those of us who owned it, as of a few months ago, got the AS: Reloaded replacement, but also got to keep our AS2. You can't buy it anymore, but it is still on the account. Sort of like how GoG handles Operation Flashpoint :p