Not to mention too that a lot of Sonic games are still stuck in their original consoles while Sega has seemly gone out of it's way to make it so that as much people can play all the mainline Yakuza games as possible since they are on pc now.
Also, side material, Sonic has a metric shit ton of comics, animes, cartoons and mangas while Yakuza (for what I know) only has the spin-off games.

Well one stood the test of time while still maintaining its core mechanics and gameplay while the other didn't.