Value should be based off quality, not genre. One 2D game may be worth paying 60$, while another isn't worth the gaming disc it's embedded on. I feel as though this is how every game should be treated.
I would also like to point out that Indie developers also make 3D adventure/platformers/puzzle games/etc. that are all less expensive than their "AAA" developer counterparts. This isn't exclusive to 2D Platformers.







