So this question is for those aiming for a higher VIP level or those already there..
how do you feel about it? Does it actually give you real benefits, or does it just make you spend more?
It really gives benefits and lowers the house net edge. It's the same when a restaurant has cashback or awards for customers that come all the time. It's good for both sides.
-cut-
I am pretty sure that your definition of "edge" is different here, because probabilities don't change when you get bonus. You literally just get bonuses, which technically can be seen as ROI, but it's not about edge probability, but just a bonus that is pre-calculated, so it always existed and that edge doesn't change.
And sure, they work like a cashback and many (not gambling) companies often gave similar reward and vip levels, so this might as well could seen as a cashback as well. But often it's not as automatic.