Type-centric means using size to emphasize relevance. When everything's the exact same size your design is flawed.
I follow 100 or so people but they are not all equal, and in my mind I associate their tweets with a reputation based on my previous knowledge. Some of my follows for example only tweet banal day-to-day activities, while others are sources of interesting links and/or their interests have a greater amount of overlap with my own. Thus, I almost always scan the avatar/username first before deciding if their tweet is likely to be worth the read. Having to look in two separate places in order to carry out this process is very tiring on the eyes.
Even better, I wish there was some way to automatically separate "boring life-y bits" and "interesting hobbies" out. I care about the boring life-y bits from people I know but not from people I follow because they have done cool things professionally.
But honestly the voting burden is too high to make it work I think. Also, I really wish things were like the 2ch/4chan model, where I could evaluate the quality of content on its own merits instead of on who said it. But that might just be too much.