Unless you are expecting to watch 30 minutes of halo there was no way Microsoft could give 90 minutes of first party alone. Garden warfare was a good stage presence for them at e3 2013 so im not suprised its back their
Look at it this way... PVZ GW2 fits well in a presentation that will be dominated by more serious / brown shooters like Halo, Gears, The Division and Rainbow Six Seige.
I think you're putting too much weight into their 1st party dedication. There will be plenty of 3rd party games at the presser.
Given EA have their own conference and PvZ isn't a blockbuster title (like COD was, for example) I think unless they have some sort of big feature or deal to tout it seems like a strange game to have, just my opinion.
Im expecting third party games, of course they'll have some, the idea that they won't show any is ridiculous and not what I said or what I'm expecting.
They will show off The Division again probably (which they will go big on) and other games they have picked up marketing for although I'm not exactly sure what they will be (Rainbow6? Battleborn?) but with all these third parties (Bethesda + Square, adding to Ubisoft and EA) I was expecting them to generally showcase their games in their own conferences unless a platform holder got something worth touting for themselves.
We can see the sorts of games that they will be showing which will have gameplay demos: Halo 5 Guardians, Fable Legends, Scalebound, Forza Motorsport 6, Gigantic(you'd think?), Rise of the Tomb Raider, Gears something are obvious, although Gigantic might just get a trailer. Crackdown could be there too and i'd expect them to have something Minecraft related. Thats a pretty decent amount of your show already
