He's important but he also has to realize what he has proven (or not) at the NHL level. He has to earn the minutes he wants.
I mean for a guy who doesn't get hardly on PP time and yes, shelter mins, he has not disappointed in the time given to him. He averaged 16:58 per game last season (sixth among Toronto defensemen). While he did not have as heavy a workload, Sandin was playing behind Morgan Reilly, T.J. Brodie, Jake Muzzin, and eventually Mark Giordano.
Last season, Sandin posted five goals, 16 points, a +9 rating, a 54.69% five-on-five Corsi-for percentage, a 58.28% five-on-five expected goals-for percentage, and a 58.17% five-on-five scoring chances-for percentage. The 1:21 per game that he averaged on the power play ranked third among Maple Leafs defensemen.
Sandin has not posted a five-on-five Corsi-for percentage lower than 52.41% or a scoring chances-for percentage lower than 52.66% in each of his three NHL seasons in addition to a five-on-five expected goals-for percentage of least 55.05% in each of his first two full ones.
For me, you only resign Giordano if you plan on moving Muzzin. I might be in the minority here, but I would gladly give Gio's min to Sandin and let him continue to develop. Now we are in the positoin we are now where the is no real spot for him to play, unless it is the right side (IF you trade Holl) and he has not looked comfortable playing there.
I totally get why he is holding out.