It's more than that. Between myself and my girlfriend, both 100% powered two wheeler riders, the only times we've been hit by cars was rear-ending - my girlfriend twice, me only once. The typical situation is a junction; looking to make sure the way is clear, the car driver - for whatever reason - expects you to have already pulled away, and they pull away while not looking ahead, and instead looking for approaching traffic in the stream they're pulling out into.
When you're on two wheels, what you want is space. Space in front of you, space behind you, and ideally space on either side. Space gives you time to react to the unexpected. One of the most dangerous situations to be in is having a car tailgating you; in that case, if anything bad happens, you die. (I don't feel guilty about speeding, filtering at higher speeds, etc., to get away from a dangerous tailgater, and into a situation where they can overtake safely.)
The easiest way to make space for yourself in the urban environment - i.e. one with traffic lights - is to filter to the front and use your acceleration power to get a lead on the traffic when the lights turn green. The idea is that you can largely stay ahead of the cars until the next traffic light. If traffic starts to bunch up, you don't want to get caught in an ever-decreasing amount of space; ideally, you want to move, safely, towards increasing space, overtaking and filtering if necessary to do so.
I've come to understand there is a difference between "filtering" and "lane splitting". 100% on board with filtering to the front when traffic is stopped at a light. It is the weaving in and out of traffic that is still moving at a good clip that bothers me. When I'm driving in 40mph traffic it is quite unsettling to suddenly encounter a vehicle moving in between other vehicles at 50mph.
When you're on two wheels, what you want is space. Space in front of you, space behind you, and ideally space on either side. Space gives you time to react to the unexpected. One of the most dangerous situations to be in is having a car tailgating you; in that case, if anything bad happens, you die. (I don't feel guilty about speeding, filtering at higher speeds, etc., to get away from a dangerous tailgater, and into a situation where they can overtake safely.)
The easiest way to make space for yourself in the urban environment - i.e. one with traffic lights - is to filter to the front and use your acceleration power to get a lead on the traffic when the lights turn green. The idea is that you can largely stay ahead of the cars until the next traffic light. If traffic starts to bunch up, you don't want to get caught in an ever-decreasing amount of space; ideally, you want to move, safely, towards increasing space, overtaking and filtering if necessary to do so.