As long as casinos write all the terms about the bonus (not hidding something), if there is complaints from players because they did not read the terms, of course the players are the one who made the mistake.
I made the same mistake a long time ago. I did not read the bonus terms and conditions before I activated the bonus. So, I called them scammers. But slowly, I came to know that it is actually casino standard to have 30x to 40x wagering requirements and count 20% wager as a qualified wager. So, I don't blame them anymore for that. But believe me, a lot of gamblers actually don't read the rules and when they see that only 20% of the wagers are getting qualified, they feel cheated. We used to play in-house games only on some platforms and we could complete the wager on dice very easily because those casinos used to count 100% of the wager.