This is the opposite of what Recurly did a month or two ago when they dramatically raised prices and the same revolt occurred. Their response was a big "F You", and their latest e-mails finally announcing even more pricing changes show they lost enough users in the process that it threatened their viability.
Flat-rate pricing works for the vast, vast majority of internet companies since the day AOL won over CompuServe because they went to the $20 per month unlimited plan back in 1996.
The lesson I've learned from Recurly is that developers find per-use to be less risky than flat fees, which is the opposite of normals.
EDIT: I guess it depends. Flat rate seems like an attempt to get more cash upfront to cover costs initially. The problem is you are leaving money on the table with large customers and you're potentially leaving a lot of money on the table at that. Flat rate makes sense up to a point but is anything really truly unlimited?
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I don't even pay my payment gateway $200/month, and they do automated recurring billing and credit card data storage too.
At the same time, the competing subscriptions-as-a-service startups already offered flat rate pricing. The per-transaction pricing Recurly offered was their main differentiator to some of these alternatives. That's the reason so many bootstrappers chose them, so switching to a $200/month fixed cost with zero notice (time to switch) and no grandfathering was a hit right to their primary customer base.
Of course I can't say for sure that's who most of their users are, but the fact that they've now backpedaled again, removed their pricing page entirely and started apologizing to users seems to indicate it wasn't a good move for them.
These services are asking for too much for what they do but I think everyone is conditioned to giving away so much to services that touch their money, that they think that they can get a piece of the pie.