You know they can't focus on all of the champions at the same time? Right now, there are other champions that require more attention, and that's why they're working on. Shen also has issues because of old elements that are no longer around; I'm almost 100% certain that he was all about the dodge back when that was a thing, and since has had to be altered so he could continue to be a tank. Maybe.
Point is he's a tank, which is weird for a ninja, who are all about assassinations and dodging, rather than being a shield-heavy tank. Putting the traditional ninja bias aside, he's not very good at tanking; his kit doesn't allow him to tank very well. The point of being a tank is you draw attention away from your allies, either by applying extensive crowd control to disrupt abilities or movement or putting yourself between the enemy and taking hits for your ally, e.g. Braum, while being too tough to be easily removed. Buffing your allies somewhere in between is a nice, if infrequent plus. Outside of his taunt, he can't draw attention or disrupt movement, his shield affects only himself, the heal on his Q does too little too slowly, and his ult comes too infrequently. Compare to other tanks, like Mundo (lots of regeneration, one slow, and a lot of damage options), Leona (A stun, a crowd stun/slow, a lunge/snare, and a shield/ally damage buff), Braum (leaps to allies, defensive buff, ranged attack block, stun passive, a slow, and a crowd slow/knock-up), Thresh (A stun grab, a crowd displace/slow, a shield/ally pull, and a super heavy slow), and Nautilus (Snare passive, shield buff, crowd slow, and trail-targeted crowd stun/knockup/slow.)
His general aesthetic is fine, even if he needs an update to his model. His kit may need some re-evaluation, but that's for a later time.
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