Seriously If you want the creative freedom to do what you want within the confines of the Trek universe. Set it after Star Trek Nemesis. Hence the past is preserved but you can dictate the direction of the Trek universe as everything post Nemesis isn't set in stone. I mean the Klingons in original series were at Cold War. The Klingons in TNG are at peace and even allies at time.
Gene was able to drastically change the dynamics because the show was set in the future and hence any changes can be justified as untold stories in between the two series
The only reason why anyone should write prequels is if you are a writer who is in love with the lore of the show and want to tell untold stories that fill in the gap of the timeline.
If you are not committed and obsessed about lore, continuity. Then don't write prequels and if they do try to write prequels then they should deservedly be scrutinised and hammered by the continuity police
Prequels Are more difficult that sequels in creating good work because of that, yet we see so many people attempting prequels nowadays
Even simple stuff like why does the ship look more advanced than the TOS and TNG when the show is set before it. That type of basic comparison can be avoided by simply setting the show as a sequel