The key difference though is the decentralization part. The backend cluster can have downtime or be shutdown, with Ethereum it wouldn't have downtime ever and can't be shutdown either.
It is 'pay-to-play', but the cost is often minimal (half a cent per transaction), nothing is really free either, when one uses something like facebook one is paying indirectly one way or another (though personal information, seeing ads, etc..)
Do you really think putting a micro payment system on any sort of interaction is some sort of success? Obviously, I think a forced micro payment is a horrible idea.
It is migrating away from a free web to something that is purchased on every page. And given that bandwidth and storage are getting cheaper and cheaper, that system is a travesty.
And not to mention, when big mistakes like what the DAO did, mommy and daddy (Ethereum) will make it all good.
Actually cheaper bandwidth and storage only make these type of systems more accessible and the micro transactions cost even more negligible. It is migrating from an illusory free web to a truly free one in both senses of the word.
Not all applications running in these sort of platforms need to be about money either, and "mistakes" like the one in the dao happen can happen in all software, it can be coded as centralized or as decentralized in terms of management as you wish, the key difference though is that the platform itself is decentralized.
Additionally, in the Serenity phase of Ethereum contracts will be able to pay for transactions, which effectively makes transactions free if you like that sort of model, is that something that would make you happier torwards Ethereum and other decentralized systems?
It is 'pay-to-play', but the cost is often minimal (half a cent per transaction), nothing is really free either, when one uses something like facebook one is paying indirectly one way or another (though personal information, seeing ads, etc..)