Pre-ordering Explorer's Guide to Wildemount, why?

Usually when I pre-order anything it is either because  a) there is a risk that the stock will run out and I really REALLY want that book. or b) there is some sort of bonus, either a lower price, bonus material, earlier access etc I'm pretty sure that there will be enough digital copies for everyone, so...is there some kind of bonus for pre-ordering?

Ok when you say  'as fast as possible', will it go slower for those buying it  on release-day?

...slower by the amount of time it takes to buy it. :D I think it's just a courtesy since it will just show up on drop day, which you might otherwise forget about. There's no other advantage.

And it cuts down on "Are you going to release Product X here on Roll20?" questions in the forums. ;-)

I also remember some very angry posts when it wasn’t known when they would release the Rick and Morty adventure. Asking two days before they released it and not getting confirmation got a lot of blood boiling when it dropped unexpectedly.

I might have underestimated the foaming mouths of the nerd rage...