I started to write a long reply, but decided to post most of it on my blog, here:
http://www.wearingfilm.com/picketfen...r-be-a-raptor/
Basically, though, my problem with the trade is that is would probably give the Raptors 5-10 more wins. Great, so now they become a 27-32 win team? Maybe the rest of the team improves, too, giving them, maybe 5-10 more wins. That's a 42 win team, at best. Maybe they make the playoffs as a 7th or 8th seed. Maybe. But unlike a much more talented team like Memphis, Toronto is going to be a first round casualty. So with a much lower pick, they aren't likely to find an impact player in the draft, and with Parker's contract, they won't have money to spend on a free agent. So the team has little chance to bring in any other players to improve the team, which leaves their best option to improve to be within the team.
I don't think there's many people that see either DeRozan or Davis as future elite players. Good ones, yes, but not elite players. And those two are probably going to be the two best players on the team 5 years from now. Unfortunately, because Parker has played so many games in his NBA career, he's likely going to start declining pretty soon. So by the time DeRozan and Davis are hitting their peak, Parker's probably just about done.
And since a team lead by DeRozan and Davis aren't going to be good enough to be a contender, the Raptors will probably continue to be a 7th or 8th seed for the foreseeable future.
So I don't think saying that a trade for Parker will doom the Raptors to mediocrity is a little dramatic. I'd say it's pretty damn accurate.