Why don't they just drive the rebalancing trucks around as mobile stations? (Let's hope no accident ever happens where a Citibike rebalancing truck hits a cyclist...)

Today I saw a new Citi bike station on 72nd street and Park Avenue. Looks like they have expanded it to the Upper East Side.

P.S. What is the function of the "hood" that covers the upper half of the rear wheel? Is it just a more protective fender? I thought it's just for the logo, but I saw someone riding a regular hybrid bike today that has a similar cover.