I have DRK fat stacks and I'm fine with the idea. But there is the point that it is meant to be integral. Why should I get better anon just because I can afford it? Well, duh. That answers itself. BECAUSE I CAN AFFORD IT. Same reason I'm buying a Tesla Model S and you're not. Fairness has not a damn thing to do with it.
But your point is still valid. I guess it really depends on how this fattens the blockchain. Those adding fat should pay a little more. And they should pay it to the people who have to host it and mix it, the MNs. But, the bottom line question is really not there... We know there is a disparity, but is it enough to care?
Is it enough fat to warrant charging more?
In my view, fat should always need a proportional price to pay to prevent bloat attacks. If someone wants to bloat the blockchain with zero cost or low cost, that's a problem. You need to penalize attackers who can add gigabytes of bloat for peanuts (in terms of cost).