Well,looking at the sequence of events, this is the right thing to do. YMX was a disaster in the first place of course... In the 60s Montreal was a thriving city of international stature - the commercial centre of Canada. Additionally, Dorval was a major stop on most trans-Atlantic services from North America, primarily for refueling. Dorval is a WW2 airport and the terminal is from the '50s. No wonder they wanted to expand!!
The politicians chose to build up in Ste Scholastique for many reasons - noise was a major concern, but also the proximity to Ottawa was probably a major reason to put it to the North and not to the South. Had it been built on the south shore perhaps people wouldn't complain so much and transportation (Metro extension?) would have been easier. Mind you with St Hubert etc nearby it is almost as stupid an idea. Forcing the farmers off their land, and then never even finishing Aut. 13 just shows the mess this whole project was in.
Just as YMX was completed, aircraft noise was being reduced and range increased - hence two major reasons for YMX's existence vanished. Then Montreal went into decline as the politicians buggered everything up further and people began moving to T.O. Now every time I return to the city it seems more depressed...
Was putting the international flights back at YUL in '97 a good long-term solution? No! It is a great short-medium term solution though. The old intl terminal and that bloody tunnel were given facelifts (dont you love the posters with sound effects?) and the main terminal was renovated at enormous cost. When they have to expand further (soon!) the cost will increase further still. A new terminal wouldn't fit anywhere as it is, and would cost huge $$.
The right solution, IMHO, would have been to build proper transportation links to and from YMX, from downtown AND YUL, move all major traffic there (inc. USA and Canada) and keep YUL as a GA / very small commercial airport, like Toronto Island for example. YMX has the expansion space and a main terminal that is vast compared with cramped Dorval. The shuttle buses from there are now at JFK and similar ones used successfully for large aircraft at IAD. They may seem like a pain, until you've walked 2 miles at LHR from your gate........ they are very efficient, reducing terminal size and therefore maintenance and heating costs.
Its sad to see it go, but the way things have gone now, it was inevitable. Some day they might re-open it when Dorval starts to burst at the seams and ADM has spent 10 times as much on it as it would need to spend to make YMX more viable........that is always the way!
As for the highways, the 20 to Dorval is no worse than the rest of Montreal... overpasses that look like they are about to fall down, huge potholes and cracks....nothing worse than the rest of the city!!