I never said he should be a main event face, but he could easily be a jobber to the stars. He can make even the worst main eventer look like gold, as he showed with his match with Kane last year. That's further than Yoshi should ever go, as he doesn't have the size, the look or the charisma to be anywhere near the stars.
He gets a strong pop during his matches, which you obviously haven't been watching. The crowd seems to be able to get into it regardless of who he's facing and support him when he makes his comeback as the face-in-peril as well as when he runs through his offense. I don't see how he needs to work on everything either when he clearly has a good grasp on in-ring psychology, knows how to sell and has offense that looks effective. Granted, everyone has room to improve, but he's certainly not bad like you seem to be indicating with no matches to prove it. Yoshi has pretty good matches with people like Kidd and Ryder most weeks, but Masters has shown, as I said earlier, that he can go by working with Kane to have a better match than Yoshi has ever had.