It would also boost the offensive numbers of everyone else in the league.
During the 1980s, Bourque was .10 points per game more productive than any defenseman not named Paul Coffey. He significantly outscored Al MacInnis, Denis Potvin, Phil Housley, Mark Howe, Larry Murphy, Chris Chelios, Larry Robinson, Scott Stevens... not a bad group of offensive performers. He nearly doubled Borje Salming's numbers. Even if you only look at the first half of the 1980s, when Bourque was a fresh-faced young gun, he was second only to Coffey and had a higher PPG than prime Potvin, Robinson, Salming, Howe and everybody else.
Any way you want to spin it, Bourque was simply the best offensive producer of the post-Orr era except for Paul Coffey... and nobody ever called Coffey the best defensive defenseman in the league.
By the way, in regard to ice time. I don't know about average, but a quick scan of Google archives produced the following:
Game 1 of the 1990 Finals - 58:26 (the game was 115:13 long)
Nov 18, 1989 - 39:40
1994-95 - 28-30 minutes per game
2001 - 28:32 in the playoffs, 29:35 in Game 7
All indications are that he played 30-40 a night during his peak.