I don't understand what you mean by shortsighted, in this case.
As long as Shawn Marion remained on the Suns, Amare Stoudemire could not play his natural position of Power Forward (because Marion was).
So Amare at Center was outmuscled, outrebounded and constantly benched with foul trouble. It went on for awhile.
Even if Shawn Marion did not become a clubhouse cancer, a whiner with the Press, an opportunity rebounder (rather than a strong rebounder) and good-without-the-ball scorer . . . it was in the team's best interest to trade the Matrix for a Center.
What's shortsighted about wanting him traded to solve that problem?
I'm not sure I would have put it the way you did, but I tend to agree with your core point. ON A D'ANTONI TEAM, Marion presented a problem. Marion is a guy with some great skills and also some major gaps. The problems he presented were:
1. Not able to create his own shot.
2. Not a good outside shooter.
3. Too small to defend the low post.
4. Wanted to shoot more even though he's not a good shooter.
IMHO, the guy Marion most resembles is Prince. Marion played mostly inside, so his rebounding has been better, but otherwise their stats are comparable:
Tayshaun Prince
Detroit Pistons
Position: F
Height: 6-9 Weight: 215
College: Kentucky
Player file | Team stats
2007-08 Statistics
PPG 13.2
RPG 4.9
APG 3.3
SPG 0.5
BPG 0.4
FG% 0.448
FT% 0.768
3P% 0.363
MPG 32.9
Shawn Marion
Miami Heat
Position: F
Height: 6-7 Weight: 230
College: UNLV
Player file | Team stats
2007-08 Statistics
PPG 15.4
RPG 10.2
APG 2.2
SPG 2.0
BPG 1.4
FG% 0.508
FT% 0.707
3P% 0.333
MPG 36.7
With the Heat, Marion's shooting went down (fewer runouts and ally-oopplays) and his rebounding went up. In any case, Marion's offense would have fit with the Pistons, but not his personality. In any case, Prince makes $9.5 million this season and Marion makes $17.1.