My point wasn't about the pricing, my point was about the availability.
If I would like to buy some older title, if it isn't one of the major names then changes are it's not available and I'm better off finding an rom and emulating the stuff instead of even bothering opening the eShop. Old consoles have thousands and thousands of games, then these digital releases are limited to tens which they happened to get lisence to. With PSX stuff, they have managed to release pretty decent list of games which work with PSP, Vita and PS3 (though EU PSN has zero way of browsing them, so thanks Sony!), so they need to keep AT LEAST the same pace and preferabely even faster considering PS2 library. Even then, almost all PS1 games I wanted to play weren't on playstation store so I needed to convert them myself to PSP at the time. So with PS2, it's still most likely easier to boot up an emulator and either throw disc in or search for a rom than even bother opening playstation store and wait for years old game to get released.
If they would've allowed physical games, this would've been great replacement for some people still having PS2 phats or cluncky emulators which aren't couch friendly at all and easy way to get some games digitally that they do not own. Now, it's just randomly picked titles to expand PS4 library somewhat.