I think it's easy to forget that this guy was cut by two teams. Do you know how much it takes to be released by a team? For God's sakes we still have friggin' Solomon Alabi on our roster! That should give you some idea. And now he's the starting PG for the Mecca of basketball, in the biggest city in North America.
As a Raptors fan I wouldn't want to sign Lin to anything until we knew what type of player he's going to be. Do a quick Player Season Search on b-r.com and you'll see that there were a bunch of (now superstar) guards who averaged 3+ turnovers, 6+ assists while shooting 45%+. Dwyane Wade, Andre Miller, Mike Bibby, Deron Willams -- to name a few. Extend it to non-active players and you have Tim Hardaway, Kenny Smith. If you sort them all together with PER, Lin is amongst the top 3. That's the ceiling, but the floor is waaaaaaay down. Remember Flip Murray? Similar situation of a guy who was largely forgotten, who bursted into the scene and was amazing.. for a couple of seasons. Another issue is that most of these guys named above were scouted all through college and what they became was at least closer to what people expect of them. Lin is pretty much coming out of nowhere.
There's no way of knowing which direction Lin goes from here on out. Mike D'Antoni offenses have historically boosted players' stats. As long as you have a team catering to Carmelo Anthony's wishes, chances are you won't see as many 20/8 games from Lin. And then by the end of the season you're looking at a point guard with still a lot of weaknesses. I'm sure many remember Flip Murray who exploded into the season and then just tailed off. We don't know enough about Lin to sign him, and we have enough question marks on our team as it is.
I'm sure other GMs are thinking the same way. Love to have him, but unsure of the future. Need more data.