This additional spending was added to punish Schundler when the measure failed. At the time they were added, the decision was made that it would not pass, and it was time to increase the cost to Schundler for opposing them. The theory was that the Demoncrats could then go out to the hustings and say "Schundler opposed your local water supply improvement project", or "Bret was against your downtown redevelopment plan".
Fortunately for the Republicans, McGreevey didn't get the memo, and called the resulting bill a "feast of porkbarrel spending" and "Trenton at it's worst". Now he cannot effectively turn around and tar Schundler for opposing a bill that he condemned. Well he can, but he would have to be completely craven, unprincipled and inconsistent. Par for the course for a Demoncrat. However, he will not be as effective.