I understand he was unhealthy and is getting a rework "soon". But if he was so unhealthy, shouldnt he have had priority over others for a rework. I mean he has been out of free week since around November 2012. Over 20 champions has came out since then. Does is really take 4 years for one rework/relaunch ?
They were needing to get the more iconic/lower-priced champion reworks out of the way:
while trying to think of a kit that would be unique and thematically fit Yorick. Hence he was left on a low priority. I am not saying that it feels great but that is why.
riot said that they were reworking yorick since 2013 but it was so hard that they didn't have a viable kit.
He is unhealthy becaus epeople don't know how to play a mele ADC, he rocks bot lane with the e+w combo
They want to keep his theme of being an undead minionmancer, hell 
doesn't even compare in terms of minionmancer to 
. And considering his whole character its a hard one to keep tied down to who Yorick Mori is in his lore.
His passive when he has all 4 of his ghouls out give him 20% damage reduction. No buff bar icon to indicate it either. His ultimate when used on someone lets them go super ham twice. Ult your team's 
she deals tons of damage AND you get a minion of her to control, then once she dies she comes back up with full health and mana to do it all over again for a bit while the enemy team has everything on cooldown.
