You're completely missing the point. This trade is the result of a simple cost-benefit analysis.
Branch has produced, certainly; and for four years, he was a tremendous bargain playing on a rookie contract. His holdout, however, meant that he wouldn't be willing to produce for the Patriots again until the team signed him to a contract of a value that exceeded Branch's production. Thus, to get Branch back on the field, the team would have to make an unsound financial decision, which is not beneficial.
A 1st round draft pick, conversely, is likely to match or exceed Branch's relative production (at least the player taken should, given Belichick and Pioli's track record in that round), and will be producing under a highly economical 5-year contract.
The move is a sound one from a long-term perspective. Obviously, the Patriots could've caved to get Branch on the field this year, but the negative consequences would eventually far outweigh the positive - Branch would be receiving more money than his production warrants, there would be less money for other players, and a precedent would be set that any contract can be altered before it expires.