I think that this situation has developed due to the fact that the main goal was gambling, not bonuses. The one who hunts for these bonuses, first of all, does a thorough research of each casino in which he is going to register. I'm not sure, but it is possible that they have some kind of checklists and tables for calculating possible profits and some solutions for maximizing it.
But for an ordinary player, getting bonuses can be a problem - the casino is not interested in providing all the information on one page, so the player must do a big research and analyze the results, otherwise he will lose bonuses due to some restrictions that he did not read.
You mean to say that it is developed because casino owners know that many gamblers are only after the money or at the bonus so they sometimes mislead them with promising words but the terms are confusing when you are about to try them so that you won't end up with a win but you can lose more money in the process of trying to get those small bonuses.
For those who are bonus hunters, those guys are wise and yes they do have those items you list above because they want to make sure that they can successfully get the bonus. Ordinary players usually don't chase the bonuses because of the bad experience they have before.
All the same, there are very few bonus hunters who can be considered professional hunters among all those players who use gambling sites. Moreover, there are few of them among those players who use cryptocurrencies. In general, becoming such a professional is quite difficult and you need to go through a lot of experience in order to understand in advance how devs will act in order to minimize bonus hunter payouts. Most likely, having considered, for example, 10 offers from a casino, such a professional will reject 9 of them. And the probability of earning on this last option will also be 50/50. In general, a professional knows from experience what devs will do in the future. And based on this, he will already decide whether it is worth spending his time on these bonuses or whether it is not worth the hours and minutes of your time spent.