Handled responsibly, the manager bonus could be a good thing. If it is used for retention of good, solid players. Some RTGs do use it that way.
If it is used in high amounts to suck in problem gamblers and to drive every player’s wagering requirements so high that it’s impossible to cash out, it’s a bad thing. Only bonus hunters don’t mind sitting there by the hour chiseling away at seemingly unsurmountable wagering requirements. The risk of ruin becomes huge. Normal players don’t even realize what’s going on there. Hence so many complaints. The side effect being that not only will players not be able to win, affiliates have to finance the whole thing, and that ends up in stats like the professor’s.