Do you think it was a coincidence that this went down once people started to spam the blockchain in the midst of the blockchain debate?
No.
The receive payments API forwards the payment with no fee, so it turns one transaction into two transactions. What if you took one of the generated input addresses and then made another forwarding address and take one of those generated address and do another and so on. You could essentially make 1 transaction turn into 10 or however many you decide to do and it will only cost the sender 1 transaction fee, the other 9 would have been paid by BC.info. It would make it a really cheap way to fill up the blocks.
Blockchain.info doesn't want to store money with them or mix coins received from different customers for different services.
Those aren't alternatives, not even close. Have you ever used the receive payments API? Just because it says API doesn't make it the same thing. BCinfo was the only service that didn't require any account/login/API key and it forwarded all payments for free, blockchain.info paid the transaction fees. There isn't a single alternative that is comparable. There are other payment forwarders (
Bitforwarder,
BlockCypher) but they all charge transaction fees and some even charge additional fees on top, also they all require accounts, or API keys.