There are regular debates on whether such paths are really a good thing. There are those that feel cyclists should just use the same roads as motorists in the same manner "as the driver of a vehicle." There are others that feel that paths are "bike ghettos" that force cyclists into sub par right of ways at slow speeds and reduce the rights of cyclists. Vast debates on this sort of thing take place on a regular basis. Compounding the issues are the designs of roads that exclude cyclists due to the high speed nature of the road and such things as dual right hand merging lanes onto freeways.

I could go on and on about this... really.

Frankly, I like well designed paths and enjoy biking them and not having to "compete" with motor traffic... I find it down right relaxing and fun. I have extensive experience bike commuting and touring, so it is not as if I only bike on paths. For some 7 years in my life, a bike was my only means of transportation. I have toured thousands of miles in the US and Mexico on bike.

I think overall, the US can do a far far better job of offering alternative transportation beyond the private automobile... the latter, which while handy, is something of a resource hog. I think we need a more comprehensive system of public transit and cycling infrastructure, and less reliance on the single person motor vehicle. But that will take a whole new focus on what transit means in the US. Some areas in Europe have a far better grasp of transportation. Several years ago I was in Oulu Finland for work and found it to be an amazing city for cycling.

Now that all said... I love the Mission Bay bike paths... and the South Bay bike paths. I just wish they were part of my transportation needs. I also wish San Diego saw cycling for the tourist potential it really is... but the city tends to think in terms of automobile... in spite of our outstanding bike friendly weather.