I'm a big fan of this stuff myself so don't get me wrong, but I think it is still a little bit worse to be locked into a cloud provider which can change rates/pricing on you any time, then being locked into a framework.
I absolutely agree with the sentiment, so don't get me wrong, but have any cloud provider ever did so? And most importantly, given that such change would impact user confidence, would it really be worth on the long term?
Of course there are several other reasons to avoid vendor lock-in, but as far as "major bad faith pricing change" goes, I believe it's unlikely.