Why are bonus terms always a whole novel?

I keep seeing a $100 match bonus with 35x wagering, a $5 max bet, half the slots excluded, then a max cashout tucked three pages into the terms. I nearly missed that bit the first time I read one. By the end, I’m wondering how much of the bonus is usable.

Should I pass on most bonuses unless the playthrough looks reasonable up front? I try to be patient with promos, but that’s a lot of rules for a small offer.

If you read the terms, what do you check first? I look for the max bet and cashout, but I’m not sure what else is easy to miss. TIA