The spin serve seems to be an interesting evolution in the sport. I guess the creator of pickleball did not want the serve to be considered a "weapon" like it is in tennis. In fact, the game is designed to put the returning team at a disadvantage, having to defend from the get go. Essentially, earning the point by defending first and then transitioning to attack later.
Here is a good article summing up spin serve
and how it is changing the game (especially) at the pro level.
I know that USAPickleball, the ruling body for pickleball will be voting on whether to keep the serve in the game or whether adjusting the rules to eliminate this type of serve will be necessary.
I personally don't have a problem with a player serving a spin serve, as long as they are required to toss or drop the ball using one hand only. I would forbid adding any initial spin to the ball by spinning it off the paddle, the handle or any part of the body. If the player is capable of adding some initial spin by tossing it up with one hand, that would be fine.