Sure, on 3rd and short you gear up to stop the run in that formation, but otherwise it is an advantage to the offense to have 3 WR and 1 TE vs 4 DB. The way a defense can make it work is if you have 1) a safety that can really cover a WR (Woodson, hopefully Hyde), 2) another safety that can really play center field (Collins yes, Burnett ?), and LB's who can handle the TE in one way or another. If you have the personnel to do it, great, otherwise nickel is your best bet.
Flip it around. If you were a DC going up against the Packers and they came out 3 WR, 1 TE and Lacy, what would you do? Would you seriously go with 4 DB?