I don't understand the argument in favor of having a central park in downtown Livermore. The argument seems to be that people will come downtown to be at the park. But in Livermore, thankfully, pretty much everyone has a park near their home. No one will drive downtown to sit in a park. People go downtown to patronize businesses, eat out, or attend the theater.
Downtown Livermore needs healthy businesses, and businesses need people to frequent them. What feeds a downtown is population density. More housing downtown is a good thing. In fact, the best plan would be to have apartments over street-level businesses, as is done in Berkeley or Manhattan, so people can walk to where they want to go.