I was really worried about the upsell too but after sailing Royal we got one person who asked if we wanted to add on speciality dining one day at the buffet and that was it. I have
DCL trying to sell me water packages\coolers more aggressively. We added on the soda package before the cruise for $10 per person.
Now we did get a steal of a deal- $790 for 2 ppl, 4 nights, oceanview balcony guaranteed (similar to DCL's VGT rates), on Allure of the Seas with a stop at Coco Cay. Did not pay for a thing at Coco Cay other than a single adult cocktail and a beach float rental (similar to what I would have done on DCL). My son LOVED the pool with the underwater speakers. The beach was not as nice as Castaway but the shows on Royal were better than DCL- Aqua show, Ice Skating show (how do they do backflips on skates while on a moving ship is mind blowing to me), Comedy shows, and Mamma Mia is as good as any National Tour I have seen of it (and I didn't need to shell out $70+ a person to see it).
I would argue nowadays Universal isn't upselling anymore than WDW is and if you try another cruise line you might also realize they aren't approaching you to buy anything more than DCL is. If you can deal with the water package\cooler pitch DCL does you will be fine with Royal.