I think we all may be forgetting some of the points of Transit City (not to be totally for it or against it). But the portion west of Black Creek is not terribly dense and I don't know if ridership warrants a fully grade separated LRT in this area. While we have now turned the easter leg of this route into a true rapid transit line (STC to Yonge and Eg) there isn't as much of a push to do this past say Jane. At best only every 2nd or 3rd train would head past Jane on the fully completed route. The only issue is a connection to the airport on Eglinton. Will this ever happen? Doesn't look too promising with the strange routing originally proposed. In addition tunneling and in median construction will both disrupt Eglinton, they will need to open the street at all stations for tunneling which is still very disruptive.
I guess what i'm saying is i'm glad the eastern leg is underground, did it need to be, probably not, but now we have a new east-west route connecting two major nodes. But in the west, why not save the money, build this portion on-grade to meet expected ridership for the next 20 years (prefer not in media) and spend our money in a more in demand area.