Of course they should. There are countless fantastic musicians, for example, who have albums that have both great tracks and filler tracks on them. Just because someone has demonstrated greatness (even consistently) doesn't mean that every track that comes out of their studio is destined to top the charts or win some sort of award.
Even the best athletes have "bad days at the office" (just yesterday, the #1 tennis player in the world lost to a guy ranked #133). Why should artists of any given medium?
Also, having good tracks will make up for the crap tracks on the album. Fans don't listen to the crap tracks as much. That's a benefit of throwing a bunch of darts at dartboard at once.
Even the best athletes have "bad days at the office" (just yesterday, the #1 tennis player in the world lost to a guy ranked #133). Why should artists of any given medium?