I totally agree that the significant lack of goals is a serious problem on SL currently.
Upon my return, I've been trying to instill this same notion of goal-oriented RP back into Kirigakure. I'm curious as to what was going on before me, because I've introduced a lot to a system that was able to absorb much.
As for who a Shinobi Legend might be, I might agree with you on Raifudo. Since he is still around, though, I tend to think the "legend" part doesn't really fit. In that case, I almost would rather direct attention to the people who are no longer around but whose name still is known by many on SL. Like... Taumaster, Baluski, KBoogi, or Lebis. If the legend part doesn't bother you, though, I definitely would say Raifudo; I'd also say Shigeo.