a casino can not just give money away. and the deposit bonus is exactly that. they are giving money away and when you do that, there will be a lot of people who will rush to abuse this free giveaway and bankrupt the casino. so you need to set some rules to prevent people just making a deposit, playing a game or two and going away with their money and reward for good as much as you can.
Yes, or without playing any game. Bonuses have wagering requirements so when you free x amount of bonus it's because you have paid y amount of commissions, being y usually x multiplied n times. The thing is, when you don't have a bonus, you just pay commissions and don't get anything back.
that is somewhat my point though.
we are talking about a Casino. and that is a business made to make money not to give money to the users. people go to gambling sites, the casinos, ... to "spend" money even if they think they go there to earn money. and in the end even if you win the jackpot you have been losing a lot of times which will negate that one win in total. either due to commissions or sheer total of losses.
that is why they make you make more and more bets because they always have the 'edge"...
Yes, may be you lose a lot from those bets before you hit the jackpot but people tend to hit jackpot and win big money instead of slowly get the profit. I do not know how are they thinking but this is the true thing. Jackpot sure is really huge but they wont let you hit until you spend more money, unless you are very lucky to hit the jackpot within no time. But this kind of players never show up a lot on casino, this is what I believe