Morally, and in principle: of course it should be on the list.
However, if we consider the argument from effect I think it's obvious that for the sake of bitcoin gaining popularity it should be left off the list.
This hits home for me. I voted "Yes" because it was the right decision, but I'd change my vote to "No" because I'm now convinced its the smart decision.
But think two steps ahead. If we remove all illegal stuff, what kind of people are we going to encourage to adopt bitcoin. The answer is your average Joe. Bitcoin gets popular - all good and well. That's step one. Step two is when governments take action against bitcoin and I believe it's not a matter of if, but a matter of when. What do you think the average Joe is going to do then? The answer is simple - leave. If we lose big portion of adopters it will cause major problems.
Not too long ago I argued the same argument, but now I realize I was wrong. We should firstly obtain a stable user base who realize the concepts and implications that bitcoins brings and not just think it's a cool new get rich quick scheme. Average Joe will have their chance to join when bitcoin is mainstream.
This is pure speculation on my part, but I don't think that removing drug markets from the bitcoin wiki is going to have a big effect on the drug trade. I think that bitcoins offer a huge advantage over other currencies for black and gray market trading. The potential is so great, that I think sellers will still be able to attract buyers without being advertised on the wiki (through other means: forums, IRC channels, word-of-mouth, etc...).
Removing drugs markets from the wiki will not stop people from buying drugs with bitcoins (and I don't think it will really hurt sales, either), but it will give bitcoins a broader appeal. I think the benefit outweighs the cost in this case.
