My favourite argument is that they should come down because "they are ugly." This is where Vancouver really needs a reality check, not every corner of the city needs or should be a high end condo market for the high middle class and above with breathtaking views. Believe it or not but the city does need some "ugly" infrastructure.
A true live work city is not the resort style condo/basic retail only model we have been recently addicted to (while this is good in spots, such as Yale Town and Coal Harbour, it should not be the model for every square inch of downtown, which it is quickly becoming), but one that includes business, industry, trains and roads, and housing for low, middle and high class.
I hate to say it, but as a city become larger, and especially when city is like Vancouver (heavily restricted by water, mountains, border and ALR) it needs layers! These layers keep a city functioning and indeed help to create unique districts.
I am in Osaka right now (my second home) and there are thousands ok km of elevated walkways, train guide ways, highways and expressways. There are actually areas that will have a road at grade, a train guide-way above it and a highway crossing above that. I hate taking my camera with me around here now (because I hate looking like a tourist) but here a few shots of a passenger train guide-way going through the city.
Pic one - Here you can see the train guide-way travelling overtop of a parking garage, what a perfect spot for such a necessary feature in a city! Also notice that other utility and commercial features have been built below.
In these pictures (taken from the train) you can see that alongside the guide-ways are offices and residential housing! These trains travel at a good 80 to 90kmh and yet there is housing beside them (and the trains are not slowed down)! Of course these apartments are cheeper then others but this allows lower income people to also live downtown (without social assistance) and maybe have slightly larger apartments for bigger families. Not everything is a luxury condo! It also allows for some offices to have cheeper rent closer to the business hearts. Good starting points for small businesses!
While these pics are not the best for demonstrating how all these viaducts are integrated into the urban fabric, they demonstrate the reality of big city living and how sometimes function has to go before beauty. I will try and take more pics of Osaka's layers and post them on here this week.
Vancouver will have to do this soon, for in around 10 years we will be around 3 million, which is a decent size population for our small area (that is, if we wish to keep our forests, parks and ALR).
Last but not least, this is the kind of market street that could also be built under the ducts:
Of course this pic also does not show it best, but we could have a pedestrian/bike orientated market under the ducts with lots of bright lights and signage. The ducts would shelter it from the rain (making it year round) and they would also stop such light from the signage from disturbing local condo towers.
That to me would be a much more interesting neighbourhood and destination (especially for around the stadiums) then more bland half empty vacation condos.