I could be wrong, and I'm not saying he doesn't feel shit to play, but there are quite a few champs where a clear weakness of theirs is "tanks ruin their day" and it kinda feels like Jax was supposed to be one of those.
Against most tanks his counterstrike dodge won't matter, and that's one of his biggest strengths. Plus he does decent mixed damage which isn't great versus tanks without Rageblade if they do itemize for both instead of pouring everything into armor, which then means if you have a balanced team comp they'll do well against your mixed damage in laning phase AND have resists for both kinds outside of it (worse than them stacking armor and dying to your AP midlaner even though the armor makes them win lane).
He probably needs some changes but I don't think the simple fact of "tanks fuck him over" is a good point to stand on. He still has his insane stick potential and his E against right clickers (which, again, most tanks are not).