Maybe so, good point. That said, the number of gamers who even play PES anymore is substantially less than those who play FIFA. Have you for example ever compared Forum Viewing totals for both forums here at OS? It's always something like 30-1 in FIFA's favor. I just checked that now as a matter of fact: FIFA 32, PES 0. So that right there says something about peoples' level of interest in PES, and in having a game they can fully edit and customize.
I still say the vast majority gamers today aren't interested in offline editing; they buy games for the online experience, and to play with their favorite players and team. And of those who do play PES, I'd suggest most only bother to install someone's patch in order to have real teams and kits. And I suppose you could call that editing and using editing tools. But the truth is, if those same people could have real teams and kits in PES by default, they'd never bother patching or editing the game. Just checked again: FIFA 40, PES 1.