It’s not crowded by any means. No, the viewing area is not empty, there will definitely be people around you, but it’s not wall to wall people like out in the hub. At all. Anyone who thinks that viewing area is at all crowded is either comparing it to years past before they added the after fireworks party when the area truly was basically empty, or they’ve never done it during holiday party season. The difference between “gen pop” out in the hub on those nights (when MK is a madhouse bc the holiday parties cut hours during the week so there’s limited chances to see HEA) and the viewing area makes it very obvious.
We just did the after party last month, on a fairly busy evening at MK (unusually so imo, EEH was that night and it was the most crowded MK EEH I’ve ever seen). Outside the viewing area it was wall to wall people and you could barely move. Inside the viewing area people had enough space to spread out blankets if they felt like it, and even when they made us all stand as the show was about to start, there was a ton of space around us. If seeing the projections is important to you (and it should be for a first viewing imo), it’s definitely worth doing.