It doesn't appear to me that there is any real lack of economically sound ideas to reduce the deficit. What appears to be lacking is the political setting to make such a wildly unpopular move.
All entitlement programs were (in one form or another) aimed at garnering long-term favor with certain voting blocks. They forced everyone else to pay for these entitlement programs, under the guise, that anyone could use the services. Therefore, for every 1 vote purchased, it appears that there would be (depending on program), 10 or more votes lost in trying to end it as they've already paid into the service. Ending entitlement programs is probably politically more unpopular than ending segregation was in the south -- something that needed to take a public-opinion-free route via the Supreme court.
The particular wording of the 16th amendment seems to make it highly unlikely the court could act on 'constitutional' grounds in this matter. While an amendment limiting taxes, would be popular among voters, it would be rather unpopular in the congress, as after it was passed they'd have to make all the politically unpopular cuts there were avoiding.