I'm confused by your arguments. One you are saying being launched into the air and slowly falling is an engaging game mechanic? How exactly is it engaging. You make very little progress from where you are and only advantage you have is getting slightly higher. You could literally slowfall back down and be fine (hence no interaction).
Secondly, your argument about a raid boss doesn't even fit this nor does it matter since you are so far out in left field with the comment that it just shows you are trying to come up with things to to say in order to say "flying sucks" without actually providing any reasons.
Here's a question, how often do you use ground mount instead of flying (where available)? Very likely you don't at all, but you'll claim you use it all the time.
How is a ground mount more engaging than a flying mount? Because you might have to fight mobs?