The consumers are as much to blame as the developers. In many ways SupCom was better in beta than the production version ever was. But it was so demanding it ran like poo on all but the best computers so they had to dial back the graphics and dumb it down a bit. Every time a new strategy game comes out, half the people are complaining that it doesn't take advantage of new systems and the other half are complaining the game doesn't run well on their toaster. Strategy games seem to have the worse time with this, my assumption is because I think their player base is older. I consistently see people complaining how the game runs on their Core 2 Duo and arguing that the previous/first game in the series ran fine so all the future ones should too.
Developers like money as much as the rest of us. So they generally try to design their product to be usable by as many people as possible. Until we kill off the toaster crowd, that means we're left with inferior games.
SupCom doesn't run well on CPUs released years after the game's release. That indicates it was a little too ambitious when it was made.
At least some of the problem was optimization - I know there were two popular third party AI modifications which made performance much better in SupCom FA. The AI scripts ended up not releasing resources after they were finished, which degraded performance eventually. Third party modders were able to fix it, or at least greatly improve the behaviour.
There was also the SupCom Core tool (forget the exact name) which rebalanced the game's threads every few minutes or so. The game only had 2 or 3 threads, and one of them did most of the work. What ended up happening is that all of the threads would execute on one core instead of spreading themselves out over multiple cores. When this core rebalancer tool spread them out over multiple cores, performance improved. This is another case where optimization could have helped.
Remember that when SupCom came out, dual core CPUs were still the most common. Quad cores were relatively rare. I don't think the programmers had that much experience with multi threaded game programming yet.
If those same developers were to remake the game using modern multi threading techniques and stuff like DX12, I guarantee it would fly, even on older CPUs.