Touch has a cast time. This means your 4 Charges have a cast time, means you can get kicked in it, get it? And you have to keep the target in range and LOS. One doesn’t simply blow a CD and boom, instant 4 charges anymore. You need something you can hurt. Gently Squeezed Toad comes to mind. And more turret caster issues because apparently Arcane was too mobile -__-
There’s also the whole “Touch being a DPS CD” thing. Taking choice away is always bad. And considering you don’t lose Arcane Charges when in combat and they start to disappear only after some time when out of combat, there might be a situation in which you want to get 4 charges NOW and sit on that DPS cooldown a bit longer, perhaps when you burn some defensive CD out of your opponent. You don’t have that option anymore. You get those 4 charges, you have to use them, as you just used “Storing 50% of dmg done” bomb on target. Otherwise all you’ve done is get 4 charges at the cost of decent DPS cooldown too.