Why Not
But what I am pointing out is that along King, going down to 2 lanes 24/7 isn't going to affect much. On the weekends, parking is not an issue. First off, its not like there is a shortage of parking in off peak hours on king, second, king in this area doesn't have the same issues (ie business) that bloor or st clair have in affecting streetlevel business. It will affect temporily parked courier etc. type services duing the the weekdays.
When I worked at Royal Trust Tower, I drove to work on the weekends (parked right outside on king). I see no issues with creating dedicated ROWs in the downtown core to improve rushhour reliabily of streetcars, especially when non-rushour traffic is pretty light, and one lane is suitable. On streets like Front, I would obviously disagree because if a car was turing, the pedestrian traffic is heavy (enough) at most times of the day where it would clog traffic. But on King when it is lighter, I see no problems. I can't remember if king allows turning, they might have to modify it so you can't during weekdays.
In addition, parking in off peak hours is pretty cheap. If 'one car lane' is good enough during rush hour, that it should be suitable for non-rushour.