I definitely think Palpatine’s return was a bad idea, but to be fair to the ST, there was “peace” for 30 years. That’s longer than the Empire even existed. The First Order’s reign of less than a year is just a blip - relatively - with the OT victory still being the larger, more important one. Especially when the new generation owes so much of its success in quashing TFO before it really got going, to the previous victors, anyway.

Palpatine stayed gone for a long time, and his contingency mostly failed.