Casinos are lucky that many players DON'T read the terms, as if they did, they would be scared off the idea of playing because they would see how the casino was making damn sure they would end up losing over the long term.
You say "reading the terms and being scared off by them" like it's a bad thing. If you don't like the terms you should be scared off by them. It's better than accepting them without knowing what they are.
You can't say people don't know the terms exist. Even the poorest written terms and conditions usually have a link to them right under the bonus offer. "Terms and conditions apply." The thing we have to remember is nobody is forcing anyone to take these bonuses. If you choose to take the bonus, you choose to accept the terms.
When we argue about vague or unfair terms here at Casinomeister the entire point is usually that they are against the rules for accreditation. If someone accepts some bullshit rule there's not a lot that person can do when that rule comes back to bite him in the ass. But Bryan can come along after and say "It's entirely up to you if you want to maintain and enforce that rule but you can't hold Casinomeister accreditation status if you do."
That's when the casino usually chooses to change the rule. Up until that point it's just a rule that's been accepted by a player and in most cases the player has to live with it.
The difference in this case is there is nothing wrong with the rule. You as a player might not like being limited to 6 or 7 dollars per spin and if that's the case you forego the bonus and play with your own money. But what you can't do is accept a clearly stated betting limit and then bet whatever you like.
The bonuses are accepted by choice and the bonus rules are part of the package.