Very true - the issue is perhaps that you need to be absolutely sure of your problem domain, and absolutely confident in your engineers' ability to maintain eventual consistency (as opposed to simply inconsistency) in the face of changing requirements. More-consistent systems allow much more freedom to change the way your system works without worrying as much about the ways in which it might impact your data storage.

You don't have to go for full serializability - you can very often get away with something simpler like consistent writes and potentially out of date reads. That sort of system scales a long way unless you're very write heavy.