Toad ends in Hell because it's meant as a fever dream or nightmare. It goes to absurdity. That's the fun.
And the new ending of Snow White is more abrupt .the witch death is even faster now, which is incredibly abrupt. Then we get an epilogue for two scenes that isn't tied to the rest of the experience. That's pretty abrupt.
It would be like replacing the "In Summer" scene from FEA with Hans being tied up with a triumphant Anna behind him. Sure, we know who Hans, but the ride isn't about him or their relationship. Snow White's Enchanted Wish is not about Snow White nor her wish.
Almost half of the ride is still devoted to the Witch/Evil Queen and the rest of the Dwarves. Her character and her wishes don't factor into the attraction until the epilogue.
Yes, but Hell also helps make the ending of Toad feel like you had some sense of payoff, some sense of falling action. 83 SW didn't have that. Perhaps because in Toad, we never actually see Toad, therefore we are basically Toad, and so when he goes to Hell, it's like we *also* are going to hell for our bad driving. *We* face consequences. Whereas in 83 SWSA, we had nothing to do with the Witch's death, really. We were menaced by her, but nothing we did resulted in her death, all of which made the attraction seem inconsistent and unsatisfying. We have less personal interaction with the witch in the newest version (undoubtedly in an attempt to make the attraction less scary), and so it's not
as jarring when she incidentally dies and we have nothing to do with it.
What's her Enchanted Wish? For the one she loves to find her. So in that sense, ending with the prince doesn't just fit the film, it also fits the ride. Maybe they could have introduced the Prince there, but then we would have either had static figures talking a mile a minute to explain things and then people would have complained about that too, and again, the prince is barely in the film (or an exciting presence there) anyway. The Frozen comparison doesn't really hold water-yes, Frozen's been around a decade and is well known and popular. Snow White has been around and popular for more than 80 years. That's considerable more staying power and pop culture osmosis.
And the counterpoint to your last paragraph: in the previous version not all of the attraction was devoted to her Scary Adventures, so if that's the criteria we're going by, that we're going to rigorously weld the attraction's name and use it to cudgel away every moment that doesn't fit the theme, than the 83 version isn't perfect either. It's less about "this is literally what the attraction will focus on the entire time" and more about the general tone of the attraction and what they want people to take from it. Enchanted Wish may not describe the entire experience, but it gets across to the guest that it has a happier ending and overall tone than its former counterpart.
Maybe it would be easier to agree that every version of the Snow White attraction has been flawed in its own way and that there hasn't been a single version that has done everything perfectly. Overall, of the ones I have experienced, I find the least overall fault with the current DL version, and judging by the poll results, I'm actually not in the minority on this.