I dunno that increasing the size of the net really solves anything. We'd see more goals, but do we want more goals for the sake of having more goals, or do we want more offense, more open ice, more displays of skill - more scoring chances?
I think making the nets bigger would open up the ice.
.... If you need one solution to increase scoring, make the rink bigger.
Thing is, you're talking many, many millions of dollars in renovations plus millions in lost ticket revenue all in the hope that TV revenue increases enough to recoup that cost.
Changing goalie equipment is the best place to start, but if it doesn't work I think changing the nets is the next option.