The bundle is set for the 23rd because it's intended for future (as in, -after- 6/23/2015) new players looking to jump into the game. There's no pre-order bonus because the intended demographic are players who don't have either ARR or the expansion; a new player given early access to Heavensward would be moot because they would log in on the 19th and need to complete the entire current Main Story Quest before they could even access Heavensward.

Near as I can tell, even in the store, the button says "Pre-Order", not "Purchase", and tells you the bundle is expected to become available around 6/22/2015 (Bundle = access to both ARR and Heavensward on the PS4 platform). I'm not sure why people are pre-ordering this bundle expecting it to give them immediate access to play on the PS4, pre-existing account or not. Pre-order is not the same thing as purchase.