This falls into the category around "deciding to care" or not. My BM66 dimpled fairly quickly compared to my old classics. At first, because I wasn't used to it, I was worried about it. After watching how they occur, I've decided I don't care. If one day I want to re-clear my playfield, great, but right now, it's so much fun, who cares? It looks great, plays great, and no one walking up to my machine even notices it.
When I restore a pinball machine, I do have OCD and at the point I declare victory (Finished!) I want it to look pristine. But then, the next moment, I want my family and friends to play the shit out of it. If it ended up with dimples from that point, fine.
Designing and building a pinball machine that gets my teenagers excited to play is an impressive feat. I'll take the dimples.