As to Sim City 2000, the trouble with that one is that it was just unplayably slooooooooooooooooooooooooooooooooooooooooooooooooooow. omg. They coded it total newbstyle. The gfx were programmed all wrong and were ridiculously slow as a result.
The gfx were programmed in a system-legal way, and were not "newb-style" at all. In fact I believe the programmer (John Jones-Steele) had a heck of a job getting it to work given the hardware at the time. It was not a simple job and he's a very experienced (and talented) coder.
I can't remember exactly what the problems were but I know there were distinct difficulties with it (because he told me a few years back).
It's because it was coded properly that we can use programs like FBlit and mode promotion and stuff. It
is slower than emulation on fast RTG machines because it was done using 256-colour AGA - so I would recommend emulating the PC or Mac versions if you have a fast enough machine and a graphics card (as they use RTG) - but the comment above about the coding doesn't do him justice at all.
