The only thing is that those 100,000 people that care about the window are the ones still playing this game daily. The casuals come and go(week in week out, also w/e we get new maps), but the hardcore still play the game daily. So when a map isnt up to the quality someone expects it to be they are vocal and they have every right to be vocal as they are the ones that continue to play the game and support the fanbase of halo 3.
Does Bungie need our support, well if we are only 100k out of 10 million perhaps not. But when they wont have the daily fanbase to support them 2 years after release, I am sure they will look back and say they needed their hardcore fans too.
Just for the record, I like Blackout. Though what made lockout good hasnt translated well into Blackout, but on its own without comparisons Blackout is a good map.