Just because Rey is the best at what she does... does not mean nerfing / removing her will induce any more creativity or variety. All you end up is everyone running GS or whatever other pure DPS character ends up showing the most potential in her place.
The only way to get actual squad variance is to reward it. Synergy should be important, and its not. Right now general purpose leader abilities are much stronger than synergy abilities. Outside of droids, there is very little reward for using a synergy team, which leaves the only option as just picking the best characters in their roles and filling out a standard DPS + Tank team. If synergy mattered more you would see things like Phasma + FOTP + FOST (yes I know ST is awful but thats only part of the problem) or Lando + HRS + ST Han competing with the standard no synergy whatsoever OB + Rey + RG.