Dimensions != graphics. If you were talking about low-graphics games, then I would have answered yes, but have you seen Minecraft? Extremely low-graphics game, but 3d. (Incidentally, also fun.) How about Psychonauts? That has horrible graphics by today's standards (and not intentionally like Minecraft, either), but it's 3d. Compare some of the high-quality graphics you see on some XBLA, Virtual Console and smartphone games that are 2d.
You're asking the wrong question. What you want to ask is either
1) "Would you buy a game with low-quality graphics in this time when we have so much graphics capability?" in which case my answer would be yes because many games do not require graphical fidelity to suck you in and entertain you. See my earlier examples, as I love Minecraft, Psychonauts, and several other games that have what would currently be considered poor graphics.
2) "Would you buy a game with 2d rendering in this time of popular and easy 3d rendering?" in which case my answer is also yes, both because games can be entertaining and engaging in 2d and because some games are actually better served by being 2d. Think about how much Sonic started to suck once he went 3d, for instance; later flops were caused by Team Sonic sucking, but even the initial move to 3d made a game whose primary mechanic was moving really fast through an obstacle course landscape impractical and unfun. Think how much more fun fighting games are in 2d, which is why, after a brief period of taking place in circular arenas, they went back to taking place in lanes in more recent years. (Some, like Mortal Kombat, still use 3d rendering, but they only do so as part of their aesthetic, rather than because the gameplay itself benefits from or requires 3d.)
In short, there's plenty of reason to still get 2d games, but even if there weren't, that has nothing to do with graphical quality as you implied.
but a REALLY fun game 
