I don't know how much of a pull a "new spanking scoreboard" would have in terms of bringing free agents.
I'm pretty sure if I was a player, I wouldn't go to a city just because "their scoreboard looks great".
Considering Toronto has a hard time attracting free agents in the first place, I don't think a new scoreboard would help them THAT much in doing so.
I think the new scoreboard was to attract more fans and such. Give Leaf fans something to look at rather than their pitiful team. and LOL at them beating the Habs 5-2.