I actually think that's exactly what makes the ending acceptable. They set the stage and open up that possibility in the very beginning of the game. Then they drop hints regularly throughout, allowing players to solve the mystery before the big reveal if they're observant enough. If the developers had not done it this way, it would have actually felt more like a copout. But you can tell they planned it from the start. The game was built around the ending, not the other way around.
My only real criticism with the ending is that there were only two outcomes, with the player getting to choose between them (usually). The events of the game only affected their dialogue at the end, and little else. If they fleshed that scene out with more endings based on your moral score, then it would have been much better received. A simple "yes or no" decision was too simple compared to the rest of the game.
BotW. I tried it out and throughout the tutorial section thought it was pretty cool. After that I immediately started noticing how empty and repetitive the game is. The more I play, the worse it gets. I'm not even halfway through the game, but 300 korok seeds later and I'm haunted by the "Yahaha!" in my dreams every night.