It's not like the price is gonna stay at 15$ forever.
Most PS2 classics started at 10 and got cheaper later on or due sales.
The selection is indeed quite small.
Hope we get some regular updates :/ and an update what happens with PSX classics.
Based on the ff7 port I'm thinking everything on ps4 is required to have full support of the modern PlayStation ecosystem I.e trophies, remote play, upscaled so it's not blurry as hell on hdtvs etc so we won't get classics like we did on previous consoles - I'm fine with that personally but I can understand why some people are disappointed.