Why in hell would I care about lens size over usability?
The newer IS system and near-macro capabilty is a big usability plus, many people might want to trade in the 70-105 zoom range if they have a 70- tele zoom anyway (and most will sooner or later). So as with the 6d, this zoom is ideal for traveling, maybe in combination with a physically short 70-300L
It's just and again the price tag that clouds the sky and the assumption that Canon does not want to give people the choice but wants to engineer them into buying more expensive gear than they'd like. And imho it's still the aftermath of the 5d3 price shock, Canon simply being greedy and thus alienating their former loyal customers.