I find it difficult to find items which are categorized as accessories on BGG since the default search excludes them. If I just search, I have to know in advance that it's classified as an accessory to know to search there.
I think the default search should include all games, expansions, and accessories. Making them a second-class citizen of the search means many are missed.
Note that the Advanced Search is also of no help, since there's no way to include accessories there, either.