How much are you willing to pay, though? Because the phone staff would be expensive and I'd bet it's a pretty tiny minority that would be willing to pay extra to hear someone's voice on the phone.
Personally, I wouldn't want them to add phone support unless it was a 900 number. That way, it only costs people that think it's necessary, plus the cost might keep away the people that would jam the lines to whine or chit-chat.
If every whiny/rant/I-hate-DH post on their sites had been a phone call, they'd never get anything done and legit callers would have trouble getting through. The people that dedicate their time to trashing the forums/blogs when they're unhappy, would be even more obnoxious with phone access.
I could be wrong, but I doubt you'll ever see DH just throw a support phone number out there. I'm surprised they even offer the call-backs--which I've never even used.
I'd much rather see support working on problems than chatting on the phone. I just can't think of anything useful I could tell a tech on the phone that I can't type into a support ticket--where the entire staff has access to my problem.
I can see advantages to phone support with dedicated servers, but it doesn't seem as important with shared. If there's a problem on a shared hosting server, they probably already got 100 support tickets letting them know it needs to be fixed... I'd rather they got to work fixing it instead of answering 50 phone calls to say the same thing the tickets said.
Then, how many calls would they get that are outside of what support handles? "How do I add a user to Word Press?" "I can't get this mod I wrote for a third-party script to work... where should I start debugging?"
But that's just my opinion. ;) As someone that's been on the other side of the phones, I think in many cases (shared hosting being one of them), offering phone support isn't worth the trouble.
If I ran Dreamhost, I can say that I'd atleast double the prices for phone support. Then again, if I ran Dreamhost, I'd probably have to raise the prices anyway to pay for all the mansions, cars, yachts, etc... 