Both really and it wasn't just me but the bulk of the Diablo fanbase (well, the active portion at Blizzcon that is).
There was an in game easter egg in Diablo 3 that strongly hinted at a potential Druid class pack. Add to this the fact that it's been over a year since the last D3 patch (a balance patch) and well over a year since the last new content (Necromancer pack). Then there's the job hirings for unannounced Diablo projects pointing to a D2 remaster and D4 based on the position descriptions. The latter two were a long shot IMHO (at least for an announcement this year) but expecting new content or a much needed balance patch for the current game where the current fanbase is wasn't out of line. Instead, they announce a WIP Diablo mobile game and nothing else for Diablo whilst every other Blizzard franchise gets some upcoming content for their current game be it new events, new characters/heroes, or a remaster that players have been asking for. The Diablo fanbase often jokes about a Diablo mobile game so you can see that it's not something that's wanted.
Even Mythor found the mobile announce to be very much a misstep for Blizzard considering the Blizzcon crowd is very PC oriented with some console supporters. I personally don't use an iOS or Android phone and won't get one just for gaming so this upcoming mobile game is useless for me.
Anyway, you can see all the chit chat through yesterday on the Diablo 3 forum here.
With zero content for Diablo that I can access, a shotgun jumping cowgirl with a pet robot in Overwatch is what I ended up finding most exciting from yesterday's Blizzcon announcements.