To that, I would say that the sprawling, suburban neighbourhoods have already been developed, and are using the highway anyway. We're upgrading the baseline capacity which any balanced transportation system in a large metro area needs.
To look at this from a different perspective, the infrastructure is merely catching up to what has already exists. Surrey, Langley and Chilliwack already have long distance commuters, who commute by car, because they live in already-developed sprawling neighbourhoods. The highway upgrades ARE catering to them, but at the same time, the tolls and extension of HOV can have a difference on how these people choose to commute.
The issue for the future, especially for ag-land reserve boosters is to prevent any more suburban development on farmland in the valley. But then
I'll refer you to the thread on "unaffordablility for families" in the GVRD. Why don't people choose to live closer to their work? Perhaps they can't afford to Live in a Vancouver dwelling big enough for a family of 4 or 5?
Its a sad state, that we're in really... many of us still value the single-family house and yard for family-rearing over high-density living... and thats why developers continue to provide single-family housing, either detached, duplexes, or townhouses.
So change that as we may over the long-term, but in the short-term, we have to continue to support a balanced approach, and that means embracing high-density developments around rapid transit, along with providing the old-fashion highways to the existing users, and commercial users.