If only gamblers use the bonus for its purpose and not the way that you said, I think no one will make this wagering requirement a big deal no matter how hard it is because the bonus is just an added chance to earn more when gambling. You won't even notice it if you are genuinely enjoying the game. But since many of us have a misconception about gambling use. We always view it as a source of income which is why a bonus is viewed as an extra chance of having profit even though house edge will kill us in long-term playing like the bonus's main objective is to prolong our game.
I agree on your suggestion and point of view in regard to the bonus.
You are not wrong however it is undeniable that some casinos have some wagering requirements that are very hard to achieve and this is what bothers some gamblers, as only by gambling nonstop they will be able to fulfill those requirements.
It is because of this that is important to read the requirements of each bonus before we accept it, as in my experience trying to fulfill those requirements takes a great deal of the fun I get from gambling, since instead of gambling just for the fun of it I will being to gamble with the idea of fulfilling those requirements no matter what.