The first one was on 1st December 1988, so this year's is the twenty third one. How many do you think have had a theme mentioning gay and bisexual men?
None. (I don't count various wishy-washy 'all in it together' themes as being inclusive, any more than only saying 'gay' as bi-inclusive.)
Aids was first recognised in gay and bisexual men. Homo- and biphobia are a big reason why the majority of HIV infections in the UK are still of gay and bisexual men. (When you read that now more people in the UK were infected heterosexually, that's down to the people who were infected in sub-Saharan Africa and later migrated here.) To have that explicitly acknowledged just once would be nice.