I think they should allow Steam users to de-couple from Steam and have some path to transfer to a normal PC license. Barring that, allow both types of keys to be used on the same account.

As for the authentication server issues, I've been playing through Steam since not long after launch and never had an issue where it was Steam's servers keeping me from logging in. I also play many other games through Steam and have never had an issue. It may be regional. I'm in the US. But it has been a solid platform for gaming for me.