Not that I disagree with your general sentiment but there are many classics with partial or full 3d. FF VII-IX, Metal Gear Solid, Ridge Racer, Vagrant Story, and many many more.
I bought Final Fantasy IX on my Vita but it runs so poorly in battle and on the overworld (15 fps) that I shelved it after a few hours. I feel that Golden Sun and Mario & Luigi are worth more money than the PSX FF games. (Which are $10 on PSN, BTW.)
Metal Gear Solid is extremely clunky and Twin Snakes makes it obsolete. If given the choice, I would rather play MGS Ghost Babel (a GBC game). I believe MGS is $10 on PSN, as well.
I enjoyed the hell out of Ridge Racer 4 when I was a kid but I'm afraid that the framerate would make it impossible for me to enjoy today.
I have Vagrant Story on PSN as well, and while the game's visuals have held up really well, I felt that the amount of effort needed to learn the game's systems and use that knowledge to play the game competently was too high for it to be enjoyable for me.
All of these examples go to show that having more advanced tech doesn't necessarily lead to an experience which is worthy of costing more $.