Only people in the valley see it as a problem because there are limited choke points into and out of LA proper which keep people from getting to work.
LA's limited transportation infrastructure prevents DTLA's homeless from getting to Beverly Hills, Long Beach's gang-related activity from getting to Brentwood, etc.
If LA wanted to fix their transportation problem then they could build trains parallel to the 405 and 110 and solve the problem, but they don't want to fix the problem because the problem allows them (us?) to keep the city segregated by income.