Yorick's Q doesn't deal the Q damage to the towers, it only allows for Yorick to proc Trinity force faster without using E or W.
Yorick is strong because splitpushing has been buffed thanks to Demolish. Yorick is strong because of how his bad lane matchups have turned to be a lot easier to win.
Fiora is a good example of a character Yorick has a problem with.
Before new runes: Yorick loses trades with Fiora and can't farm outside of tower without losing 10% health(give or take 5%) Yorick rushes a Thornmail and falls behind because he can't splitpush very well without Trinity.
With new runes: Yorick out-trades Fiora pre6. Yorick can trade with Fiora more safely in lane phase. When yorick gets to Fiora's tower, even though he still has to rush Thornmail, he doesn't fall behind as much.
That's only one example of how the new runes have helped Yorick become better.
Let's just take a look at what it is that makes Yorick...Yorick.
Pros:
Splitpusher
Great Duelist
Can 1v2 with ultimate
Sustain
Good Peel
Can make Terrain
Cons:
Being behind (used to be a huge burden) but now it's not as bad.
Slow movespeed
Weak pre-6
Has low 1-6 stats
Super Kite-able
So now we know what Yorick likes to do. Any Yorick worth his weight in gold will be garunteed to take Demolish within his runesets. This helps his Splitpusher identity.
Any other runes are up for grabs for yorick. Ultimate hat? have maiden out more. Celerity? That extra 100 health will help him deal with his bad matchups better. Magical footwear? Free boots say Yorick gets more effective gold which means more gold efficient which leads to better splitpushing.
The only thing Demolish does is force enemies to build Sunfire and Warmogs.
Those two items together stop a Yorick from splitpushing entirely and nearly EVERY toplaner can take those two items.
Granted Sunfire isn't good in fights, but you aren't looking to duel one of the best duelists in the game, are you?