Even for gaming and workstation use, this seems to be true. Last year, the value proposition of remote desktops looked great, but it turns out price/performance of all computing parts was at an all-time high.

I looked into this and found, annoyingly, that even if used the Remote Desktop rarely and I could deallocate the machine to not get charged, it was actually the price for storage that made it too expensive.

You could say that same about running off-line batch jobs on EC2 instances. Unless your co-located data sources are forcing you to do so, I cannot fathom why you would.