One of the biggest changes promised for Twickenham is that it will become a destination, and not just somewhere to drive through. But take a look at these two photos, and tell me where you’d prefer to come and have coffee and shop: (both from Horsham, by http://aseasyasridingabike.wordpress.com/)
Because the people who wrote the Twickenham plan would rather get the traffic through – in the mistaken belief that through traffic generates business – than make it nice for people to loiter.
People's Front of Richmond 
The Council claim that TFL forbid them from reducing road capacity. (to be fair without a by-pass you couldn’t eliminate through traffic). Why they are actually increasing capacity in London Rd is unexplained.