You wouldn't necessarily use this if you expect to keep all the systems running 24/7; for that, another provider would indeed be better. You'd use this if you want to scale up or down and boot different images on the host. Yes, you have a 24 hour minimum, but that's better than a 1 month minimum.

I'd have loved to have seen mac pros, and virtual instances (subdivided, even if you had to maintain a dedicated host to run them on), but this is still a major quality of life improvement for heterogeneous environments.