This is worth taking very seriously, not only as a complaint about an unbalanced biographical article, but as informed criticism of Wikipedia.
McKellen himself has a good deal of internet savvy and, during filming of the Lord of the Rings movies, ran an excellent blog complete with his own photographs taken during the production, and very well written diary entries about the history and geography of the area of New Zealand used for filming and production. For a time it was my favorite website to visit. Looking at it again, I see that he now has a very good autobiography up there.