No, I don't understand why people really wanted it. What the hell do you play Skyrim for, that you should actually desire this feature to the extent that you'd be legitimately disappointed that it's not added?
He's not disappointed that it's not added, he's disappointed that it was advertised as a feature, but was implemented so terribly. If it hadn't been advertised as a feature added by the DLC, he wouldn't be disappointed.
It's not something I would ever really use, but I fully understand where the OP is coming from. Did you honestly watch the trailer an expect dragon riding to be implemented as it is? It's completely pointless and stupid. Like, there is literally no reason at all to do it, it just makes you way less effective. It's terrible. I don't think it's unreasonable for people to be disappointed in it. To say "if you're disappointed, it's on you" really shows a tremendous lack of understanding of just, like... being human.