Wow..Too many stuff here :-)
Do you guys think that something like that: uservoice.com/feedback
would help you sort those things out better?
Anyhow I'll add mine here too:
MAJOR
OpengGL
Simple Networking
Particles
Simple Scripting (javascript) possible implemented as an action.
iOS
Attaching Event Sheets (scripts) to Objects
as to have total control of an instance and make way for bigger projects.
No 3D (sorry)
Even if I am a 3D guy mainly I would like Construct to stick to 2D and excel in that part. Consider Unity or GameStart3D!! for 3D projects.
Simple Timeline Editor
Simple 2D Draw actions
mostly for debugging and quick ideas
Collision groups
A simple(?) implementation could be based on layers, so every object in a layer collides with any other object in that layer only.
MINOR
Change Pivot in Layout Editor
Ability to pick the parent of a pinned object
Proportinal scale in editor (less minor)
Seperation "line" where the events of a Group end
Ability to dublicate ImagePoints through the entire animation frames.
Sorry for long list. Construct 2 is great but you asked for it :-)
I've ommited things that I believe will be there at C2 v1.0