Are you really considering taking that good camera with your telephoto lens to the beach around all that sand. If you are they you are going on a picture safari, and not a trip to the beach where you will do any beach activities.
Don’t think you will find pricing better on any other mass market line, especially for excursions, casino, spa services, restaurants or drinks. If that is your criteria you need to explore land based vacations.
You do not get access to the thermal suite when you use other spa services. Daily passes are rarely offered, in fact I’ve never seen them offered, but if they are it would be for port days.
The food on board the ship has never been better than mid level chain restaurant quality even in the specialty restaurants. Not sure where you get the idea the the MDR food is worse than it was. I haven't noticed a change in quality in 15 years, it's always been mediocre.
Rates on new ships are always more than on old ships, it’s been that way for the 20 years I’ve been cruising NCL. In addition menus have changed every 4 to 6 months during that time and will continue to do so.