In my view there is a clear reason that Bonus T&C's are taking this steep downhill road after years of having steady WR of 30-40x B.
The number of multi-platform casinos is literally exploding and with that the amount of BAs + APs.
So what operators are doing first is raising the defense walls. First a little, if there is no improvement a little more, etc. etc. up to a point were taking a bonus becomes absolutely useless as the DO's and DONT's list is so long that a player is exhausted by the time he finishes reading it and on top has lost the appetite to do a few spins.
The Chance Hill case was the best example.
I read some T&C's yesterday that went like this:
"During an active bonus, you are not allowed to enter or play: Blood Suckers™, Kings of Chicago™, Piggy Riches™, Dead or Alive™, Devil's Delight™, The Wish Master™, Robin Hood: Shifting Riches™, Jackpot 6000, Mega Joker, Secret of the Stones™, Jackpot games and/or Live Casino Games/ Live Dealer." So now even just entering one of the prohibited slots will see your winnings forfeited.
And another good one on some no deposit FS on registration:
"Maximum Cashout: EUR 10.00. In order to withdraw winnings from non deposit Free Spins a minimum deposit must be made, which needs to be wagered once." So you are allowed to withdraw a massive 10 bucks from the FS winnings after completing an arduous 55x WR and now they ask for a minimum deposit which has to be wagered as well once before withdrawing the 10 mediocre bucks. If you are unlucky you will have lost those 10 bucks by the time you're done.
My recommendation stands:
Avoid bonuses whenever you can!!