Between shield stun and acceptable spacing on the opposition's part, when is Yoshi really going to benefit from jumping OoS anyway? Parrying and a slightly faster roll would more than make up for that particular downfall, IMO.
EDIT: That was a serious question. Really, of all of the changes that Yoshi could get, why jumping OoS? Keeping the larger, squishy vBrawl hitboxes, for example, would be so much more helpful than giving Yoshi the ability to jump out of his shield. Not being able to use an aerial OoS can be a bit annoying, but it's one of the many traits that makes Yoshi a unique character.