Your problem is this?! Really? You’ll be the first one to pre-order it then. No need to confess that.
If you wanna really know, that’s a sequel you’re talking about and its advertisement campaign will be longlasting and more expensive compared to a new IP or an expansion pack for WoW that they crap out every once in 2 years.
This Blizzcon they needed some positive press so they rushed the announce without any reliable release date; I expected D4 to be announced next year with a release date to be honest. Thanks to shill media drumming for Diablo 4 hype we get left in the dark.