Not sure why it has to be without EC2 to be useful. The main benefit is indeed the fact that you can have VMs, queue, load balancers, databases, DNS, cache, etc. all using consistent APIs, etc. You can create dev/test environments that are as close to prod as possible with fraction of the cost, etc.
In our case (and I'm pretty sure we're not in the fringe) when you consider all costs including the administrative overhead, etc. EC2 costs are not significant portion of the cost.
Just to give an idea, for us, even if someone had offered VM hosting for free, it would not be cost effective for us to move.
For a company that have very high processing requirements it could be a different story. I just wanted to mention that the value added by services in addition to EC2 is sufficiently high that even if EC2 costs are higher than alternative (and they are higher), AWS can still provide significant savings.
Time of a highly skilled dev/ops person is (very) valuable, and not something we can buy more of easily. Anything that saves us time, implement faster pays for itself pretty easily. If you don't have a massive EC2 bill, chances are AWS overall is a good proposition.