This is just my specualtion also
1) There QB is bad therefore they need to spend the money on better defense of players.
2) There QB can't throw and a big name wide receiver would get upset and cause problems (EX OWENS, TERELL, JOHNSON, CHAD)
3) They made a mistake and drafted a good college QB with Horrible throwing mechanics and tried to make him a NFL QB. OOPS they also drafted Adam Jones guess they were trying to be REBELLION.
4) What Justin Gage and his 2 TD catches last year he is a big name recevier def better than Moss, Owens, Smith, or Johnson.
5) Big Name Receviers don't really like to block. The Titans receviers just need to block for there RB and QB.
6) Vince Young's errent passes is going to get a big name wide recevier hurt going over the middle on a inaccurate pass. They don't like that
7) Vince Young is bad
8) The Titans offense is woeful (see playoff game VS San Diego ouch)
9) Vince Young
10) The Owner is cheap really cheap
11) Kerry Collins he is a drunk and a racist
12) Albert Hainesworth might get upset during drills and stomp on a "big name" wide receviers face. They don't like that. Ex Chad Johnson wouldn't look right missing an eye with a huge bandage on his face doing Degree commericals. WOULD HE???
13) Vince Young now has to drive to Dallas to go to the scrip club with pacman so he can be rebellion.