MTX isn't controversial at all in my opinion to be completely honest. If Jagex wants more money and wants to make RS P2W, it's completely their prerogative. They don't specifically have any obligation to cater to free players or even players in general (of course, if they abuse this too much then people will actually quit; however, for RS that threshold is probably extremely high).
I just know that in the many games with MTX I've seen, people almost always whine and threaten to stop playing; however, they never actually talk with their wallets because they're either too addicted or just can't bear the thought of falling behind in the P2W race. This is how all of the chinese/korean cash grab games operate. In RS this is prevalent with many people going for max XP rates by rolling for all the outfits and whatnot from TH. For every person like @
KeepBotting; who might be able to actually quit over a disagreement over MTX there will be several who are not able to. RS addiction is like smoking, when I used to play it; it was like a cancer that I knew was bad but was powerless to stop. That's why I sold my accounts.
In terms of money made from MTX, I'd be willing to bet that they make more money from MTX than they do from RS membership. It's almost guaranteed that this is the case as there's always those that are willing to (or don't know how to stop) spending obscene amounts, they're referred to as whales. It's explained pretty well in that South Park episode about MTX/micropayments.
/rant