It's a bit unfair comparing mid 80s technology to late 70s technology. The transistor budget difference is quite a lot.
The C64 was nice, but it needed a configurable colour palette rather than the mud-themed palette it had.
The Spectrum would have been okay with hardware sprites and a configurable palette. But it didn't have them. Nor hardware scrolling. So it sucked unless the game was designed with them in mind.
The palettes didn't need to be amazing, the Amstrad CPC did well with a 27 colour palette (but cocked it up by having a 16KB bitmapped display).
