luckily nobody is forced to use the trail. there are surface streets (granted, hilly ones) that can take you from the UW area to bothell...
for instance, since i hate the BG trail as well, i skip it by going up 5th ave next to I-5, then take perkins/180th down to the BG trail near lake forest park.
from there, you only need to be on the trail for a kilometer or two before you can break off on juanita or 100th ave (to complete the loop).
so, the solution is to not be part of the problem. i figure unless you're just starting out, or are walking, then use the MUP.. those paths are for old people and strollers, not fast bikes.