Just some thoughts on this:
I get where you're coming from, and I too would welcome a plug&play solution. That said, I believe they're already working on something like that, so it might just take a bit of patience 
In the mean time, this might be something that interests you. That should install an entire offline toolchain, which you can use as you please:
I think it's not really reasonable to expect Particle to release a full-fledged IDE, since that's not their main business. There are companies out there that exist solely for developing an IDE. Added to that comes the fact that not everyone likes to use the same IDE. Some folks like eclipse, some VS, some netbeans, and so on. You couldn't possible satisfy them all with a single IDE, and therefore I'd argue that effort is better spent elsewhere. That's not to say that the IDE's Particle has shouldn't work, but perhaps shouldn't be as feature-packed as some of the big ones out there.
Try clicking the 'ready' at the bottom after verifying. It should show you the size.