The reason as always is earmarks. Congress feels that it is their right to direct some spending to their district and under the Constitution it certainly is. Even when one party is out of power earmarks are still available as the legislators understand that they need to help each other. One day as there has been in the last twenty years the parties could switch sides. The difference is that the major party gets more of the earmarks.
Earmarks have also been one way that the smaller states get their fair share of Federal dollars. Hawaii is a good example. It is a rather poor state overall with a small population. It's two long-serving Senators have directed millions in funding to various projects and entities in the state. Defense spending and investment in the Islands has especially been important.
Obama attempted to restructure the defense budget overall by ending several large procurement programs. These included the F-22 Raptor and the second source for the engines needed by the F-35 Joint Strike Fighter (JSF). Both Hawaii Senators, Inouye and Akaka, have supported these programs. When Congress as a whole gave in on the F-22 they continued to vote to keep the money in the budget.
Congress has continued funding for the second JSF engine as well as the VH-71 program despite Obama's request that they be terminated in 2009. If they are not removed in Conference then the final bill will contain this funding. Obama has threatened vetos but in reality it would be hard for him to do so with such an important funding bill with ongoing operations in Iraq and Afghanistan.
To end the process of earmarks and continuing programs not requested by the military or the Executive Branch will require an attitude change in Congress. The idea that states are entitled to a certain level of funding or that a district must keep programs going despite budget requests supposedly based on a real requirement must be stopped.
Of course this would then mean that areas and states would lose funding that they have grown accustomed to use to pay for services and programs. The "Stimulus" bill so far has mainly been used by the states to balance their budgets and keep state workers employed. Many teachers and police stayed on the job thanks to the extra money from the Federal Government. In a way this was one large earmark with a great deal of discretion as to how it could be spent by Congress and the states.
Unfortunately the chance of future stimulus funds are limited with the massive deficits the country is now facing and collapse in tax revenue at all levels due to the economic downturn. If the recession continues for several more months 2010 may be worse then 2009. This means that states will turn to the Federal Government and their legislators again to make up the difference.
Earmarks in the eyes of Congressmen are jobs and economic stability and growth. They are not going away anytime soon.