Another benefit is that it probably is a small "pre-load". When the full game is out, just put the demo into the directory and very game cache. Should work.

Considering your name I assume you play mostly games from 80s and 90s?

To answer your question however: because of the engine and its graphics. What else?!

I also assume those ingame cutscenes take some space especially if they're not compressed.

I watched a gameplay video of the demo on YT. Looked really good. One question though, do we know if the missions are (somewhat) randomized, or is the 2nd mission always going to be a choice of Baltimore or Hong Kong? Or can it be two completely different locales, varying for each player?

If you are asking about the demo, it seems that there are currently only 2 mission files, so it will always be the same 2nd mission, and I think choosing the other region won't make any differences :(
I'd suggest going through the ini files to up the difficulty if you want a bit different 2nd time, or just try different tactics.

Surely it makes sense if it's always the same in the demo and that's completely fine, I was just wondering if anyone has any word from a dev that the mission structure / locales are randomized (in the final game). It would make sense if the game wasn't completely linear in a way that the mission choices are always the same (plus it would be much more fun if they weren't).

From what I recall reading in the 2kforums, the missions will be random, with a choice of 1 mission out of 3 possible (3 may be dependant on difficulty level). You make one country happy, and 2 countries' panic rises. As for random missions, again, best comparison is with the UFO:A? games. A small set of missions (vip escort, search and destroy, bomb defusal, maybe a few more), with a smallish map variety, combined with a number of possible aliens. Add to that the crashed ufos, and you will have a random game.
Though once more, no idea about story missions, since they did try to keep the discussions as spoiler free as they could, so I've no idea about what those may be, if any.

Ok, thanks for this info. Sounds really great! Maybe even pre-order worthy, although I still might wait a little so that the initial price lowers. I've got plenty of D&D games from the recent promo to keep me occupied until then. But I'll definitely get this at some point.

Ouch the demo gets to about 1% and then hits dial up speed, I wonder if the steam servers are currently being overloaded?

Last night that I got it I was getting ~1.2 MB/s (normal for my home line), so I'd suggest trying to change download location. I can redownload it and tell you if the speeds are better if you'd like though.
Edit: I'm redownloading it, speed seems good, so it's probably the download server you are using that is getting hammered :(

I love it when they release a demo before the game comes out. I've been on the fence with this, so I'll give it a go and make my decision...

After leaving Steam on overnight to download the massive demo, of course.

That seems to be what I am going to do as well

Runs like a bag of bricks on my machine :(

MASSIVE delays doing...something with half-a-gig of RAM.

Looks like it'll have to wait until I can be bothered rebuilding a decent rig...

Well I got Seattle or Beijing, even in the demo, so I guess it's random.

US or China, which seem to be the only 2 possibilities. But at least it does have a list of cities, not sure if the map location also changes depending on which city you go to.

I was pleasantly surprised that it even runs quite nicely on my laptop. This makes a huge difference to the amount of time I'll be able to play it.

Things are not looking good for the four MMOs I'm currently juggling.