I visited WDW for many years pre-FP, and I stood in line without complaint. In the post-Fastpass world, I will once again stand in line without complaint, but that doesn't mean I don't think that WDW is making a huge mistake by replacing the legacy FP system with FP+.
No, WDW doesn't "owe" us Fastpasses, but nobody expects their WDW touring experience to get worse or less efficient over time, instead of better. WDW didn't have to add Fastpass in the first place, but it did, and those guests who made good use of it understandably came to rely on it as a perk that was rolled into their ticket price, and which added appreciable value to their vacation experience. Now its value to those guests is being significantly diminished, and unless WDW drops ticket prices to bridge the gap (which we all know isn't going to happen), those who came to rely on FP are entitled to be disappointed that they're paying more money to see less and do less.