Its still not as good as a GBA emulator and i am pretty sure unless you wanna download the entire CD that is freaking huge, you gotta buy that CD anyway whereas the ROM image is much less in space and easier to find, that and GBA is newer than PSX therefore its easier to find a cart than a PS1 CD depending on the stores.

I am just saying its more practical (at least for me) to download Cart ROM images than a CD, or buying one.