I can certainly share what I think are valid reasons to remove the Viaducts. I can't speak for Meggs and co, but there is plenty of info out there for their rationale. As far as I remember, this pet project would not necessarily cost a hundred million dollars, as the sale of city land will offset that quite substantially.
First I feel I must re-state my position. I think the Viaducts should remain in place for as long as their reasonable lifespan. I think eventually one or maybe both should be removed, and we should be planning for that eventuality. I am not a stubborn zealot with my views, and I absolutely think there are great reasons to leave them be. My issue at times with the discussion in this thread is the idea that anyone that is pro-removal must have ulterior motives or must be some deluded anti-car hippie.
So here are what I would call valid reasons for removing the viaducts:
The main reasons for the viaducts in that area do not exist anymore. No freeway was built to use the full capacity. The land underneath is now somewhat developed, so a raised roadway is no longer absolutely necessary.
They are only around four blocks long! If they were longer, I could see how being able to by-pass intersections would increase efficiency if there were more than two or three.
I don't like them. I think they are a bit of an eye-sore. I don't hate them, and I actually love using the bike lane to get in to downtown. I just think the area would look a lot nicer without them, especially when the surrounding area (especially creekside park) is developed. The eye-sore is mainly underneath the Viaducts and around the escarpments, so I know that could certainly be addressed without removal.
I think the proposal that won the viaducts idea competition is great, and an improvement. Especially in regards to Georgia Street.
I'm not pro-developer, but I sure am pro-development. So the idea of that area being used better (subjective, I know) resonates with me.
I also sincerely believe we are heading in to different times. Driverless automated cars are the future. Safety and efficient use of road-space will be the result. The increasing emphasis on town-centres and walkable communities will hopefully result in people living closer to work.
-------
I firmly believe that removing them must make sense for the region and not just the immediate area. With that in mind, I don't think they should be removed without addressing concerns with the movement of goods, and the impact on streets like Prior/Venables. If studies proved the removal impractical for the region, I would absolutely accept that.
-----
So those are the main reasons I see for potential removal.
I don't think anyone will read this and change their stance on removal, and that's not my intent. I merely believe there are a few legit reasons to remove them. Perhaps there are more and/or better reasons to keep'em, but that argument is not served by completely dismissing opposing views. Which was really the only point I was trying to make the other day. I am far from an expert on the issues that frame this decision, so you can certainly view my opinions as those of a layman.