I guess my theory is the more reasonable ones probably just remember 40 year old Lidstrom and Bourque, not the prime versions. People were super mad about Lidstrom's last Norris, and mocked Bourque for team hopping because he wasn't 'good enough' to win on his own. That's to say nothing of Orr, Potvin, or any of the other greats. Hell, you'd think they remember prime Pronger even, mayyyyybe Chelios, but nope.
I dunno, I'm just a big follower of defensemen in general, and I think most of this generation's d-men have one big flaw that will keep them out of the Lidstrom/Bourque conversation, and that's all-around game and longevity (especially with respect to Bourque). Keith is maybe the most well-rounded acclaimed guy of the generation frankly, and even he is short on the longevity side compared to Bourque.
Or his career cut short due to concussion.
Underrated aspect of Orr's game--he could **** people up on his own.