It all depends on the casino and the terms attached to the bonuses on offer. As long as players are made aware of the wagering requirements, then I don’t see a problem. Decent casinos and portals for that matter too, will provide this info.
As a player whenever I accept a bonus, I always play with annihilating the WR attached in mind. Therefore depositing what I can afford to lose, but upping my bet stake to high amounts, should I get a half decent win. With the sole goal of meeting the WR ASAP. It works as well.
Just yesterday I played at an MGS casino I didn’t have an account with, deposited all told $650 and received in the process $250 by way of bonuses. Thunderstruck at $9 a spin and 5 hammers came in 
Ended up cashing out just over $2100.
Now just waiting for the bugbear of mine that is the reverse withdrawal period to be over, hence working from home today. As I don’t have the casino installed on my laptop or the account details here :colgate:.