As an avid Twitch lover, I somewhat agree with your suggestion. But I also somewhat disagree with your argument against the current buffs.
Since Twitch is the ultimate late game hyper-carry, you HAVE to have some sort of give and take system in place, that's where his horrible early game comes to mind. Giving Twitch any sort of early game power would tip the scales too heavily in his favor, then all of a sudden all you would see is Twitch, and then what happens? Twitch nerfs.
Lowering the cost on his Q is a very easy way to make proper poking use of your E very rewarding, as it's a very mana hungry ability in the early game, and your Q is now lower cost, which means you'd actually be able use it after a trade, or all inning at the wrong time.
As far as boosting the damage on his ult, it's not a huge buff, no, but it's still a few more points of damage that he didn't have before, so I'll accept it.
Now, for your suggestion, that's something that honestly will never happen. Twitch's passive does true damage, so having it spread like wild fire would be detrimental to the game, more than it would benefit the game.
Basically what I'm saying is, accept the small buffs, don't ask for more, because as long as you keep up with your farm on Twitch, and make good use of any kills you might be handed, you're going to scale harder than anyone else, and be an absolute menace in the later stages of the game.
