I think you have to look at it compared to a subscription game, Jada. The diamonds are VERY expensive, even on a double diamond sale. For 100 dollars in RoM, you get around 6-7K diamonds depending on the sale. Anyone who's anywhere close to endgame (And those who aren't, too, probably), knows that 6-7K diamonds get's you SO LITTLE in this game. I mean hell it costs 4500 diamonds just to get ONE single X rune in every piece. God forbid you need 4 X runes in a piece. 18K diamonds
From my observations, another reason that the game is so expensive is due to the unrealistic expectations of diamond buyers. There's often a mentality that dropping a few hundred dollars in this game will allow you to buy your way up to become as OP as those in endgame guilds in a week without having to do any farming yourself, and that simply does not happen.
I've seen many diamond buyers sell all their diamonds, then try to buy all the stats and gear they'll ever need. Then they realize that the $200 they dropped got them 4 pieces of gear, and lose faith. People need to realize that, even as a diamond buyer, you're going to need to farm the majority of the stats. Your one advantage is having diamonds, which F2P need to buy with gold that they spent even more time farming for. Stats you buy should be used for finishing touches on your gear - you shouldn't expect to buy every last stat on every single piece of gear.
The second being, selling no realistic amount of diamonds will allow you to "buy" your way to having the same gear on par with the top players in endgame guilds without any extra farming yourself. I've met too many people who looked at the clean T9, orange statted, X runed, +16 gear of top guilds and thought that they could do the same if they sold enough diamonds. It is simply impossible to buy EVERY last item with selling diamonds, with orange stats costing 60m+ each and the sheer cost of X-runes and clean tiering. Its not a task that can be completed with your diamonds alone, period. (Unless you have exceptional wealth).
One thing Gameforge CAN do? Get RW to change the way drops are in easy and normal. Easy mode needs to drop sufficient gear and stats that players can use to progress to normal.
Normal mode needs to be appealing enough to progress to. The majority of Normal runs often end with 1-2 people getting 1 decent item/stat, and the rest of the party gets nothing for their efforts. Decent stat drop rate needs to be drastically increased, and the same goes for Mentos too (AFAIk, mento items don't even have decent stats anymore).