Well, normally I would agree with you. However, seeing as the Annuals I've edited are parts of an event that ran through annuals that were released over at least four months, more conventional cover dates can (and I feel should) be used to establish a proper reading order.
Well, for the reading order it is established in two places already:
below the story credits: Previous issue:(story) New Mutants Annual #4 / (story) Fantastic Four Annual #21
and in the event page:
http://marvel.wikia.com/Evolutionary_War. The month implies there is a month on the comic.
You know what? Let's take this most recent one as an example. Every other Atlantis Attacks annual (all 13 of them) except for Avengers Annual #18 already had a month listed on it's page. Seeing as I'm clearly not the first person to do this & you're so affected by this, please kindly remove this information yourself.