I'm currently doing a B2B on Prima and agree with your points. I do have perspective on spring break vs non and the deck 8 Ocean Walk over crowding issue. Last week, we had over 600 kids on board. There was literally no place to sit at either the pool deck or on deck 8. I couldn't get a Vibe pass last week and on sea days, I'd walk for an hour looking for somewhere outside to sit. This week, very few kids and still pretty much every lounger has a caboose sitting on it. Way too much real estate is taken up by Vibe and The Haven.
I think deck 17 (pool, buffet, Vibe, Observation Lounge) was designed by someone with a substance problem.
Although the staff has been excellent, the price would need to be really great to get me on a Prima class ship again.