Key escrow came up back then though I don't think it included needing multiple keys in order to decrypt - not sure if that's mathematically possible or if there's another reason that never came up. I suppose to the government that's not much different than still needing to compel individuals for the key.
Your point about companies is interesting since things like iMessage could be MITM currently anyway to get unencrypted content for government requests. I think most people don't necessarily trust the company behavior here though and given the government's recently revealed behavior with National Security Letters and secret, massive, unwarranted data collection I don't think they should get a pass. I'd rather side on the power structure unable to collect some of the information even if they're unable to investigate.
I think fundamentally introducing multiple ways to get keys takes a secure system and makes it insecure - the access no longer rests on one individual's knowledge. In general I think that's a bad idea - it also doesn't prevent people who want to actually encrypt their information from doing so (it just harms the regular public and dumber criminals).