Why Zac Q change made Zac top unviable

I finally understand why Zac top and mid is not fun anymore, while Zac support is at least fun in the laning phase. Stretching strike used to be your precision farm and harass tool in the lane. You could use it to last hit multiple minions and hit the enemy lane champion at the same time. Right now, the Q is terrible at last hitting more then one minion. I frequently find minions dying before the slam happens, so I can only really use the Q to last hit one minion at a time. If I do that, then I can't use the Q to harass. It means I have to chose whether I use the Q to harass or to farm. The longer CD makes that choice even more frustrating. The reason why Zac support is fun, is because you don't need to make that choice. You can always use the Q to harass since you aren't trying to farm with it anyway. Just wanted to share that insight as another reason why this rework made Zac less viable in top and mid lane.