The preordering of a physical copy is only really a necessity when it is something that EVERYONE wants and you only want to go to a store. Which isn't really a problem for PC gamers. But imagine if you wanted a copy of Halo 5 from Gamestop on launch date. A pre-order would be smart.
That being said, things like Amazon and the like make this a moot point.
Beyond that, it is just about being able to play it sooner as opposed to later. The preorder will (well, it used to) result in you receiving the game on launch date. The preloading will result in you receiving the game on launch hour. And that is one case where automatic Steam updates are GOOD, since you get those last few bits automatically. Thus, it is playable when you get home.

I occasionally preorder games from physical shops, not for the 'must have it now' thing, its more just wanting to avoid the pain in the arse situation if I make the erffort to go there to buy it and they have actually run out and then I have to wander around town looking for another shop that sells games and hope they have it
Laziness, pure and distilled. Its an art form I think

With my Internet connection it's always faster to decrypt than download. MI2 took 3 hours to download at my house.

If I wait until the third one can be pre-ordered do you think I'll be getting this one as a pre-order bonus? :P

It's $16? Must be aussies getting screwed again, I just checked my store and even though the price is converted to local currency there, it checks out as $9.99.

First impressions:
Awww! They cut the credits sequence! Oh well, at least the HD remake does look and sound pretty damn good, even if iMUSE seems missing, replaced with more "modernly traditional" (heh) transitions. Strangely, it seems to be lacking in classic mode too, which is another disappointment. Other than that, what I have played so far seems good. The cut intro sequence is bad, true, but as I still got my own SCUMMVM version, it is not the end of the world.
So, I'm still having a great time despite those shortcomings, which are minor when it really comes down to it. The voice-work have lived to my satisfaction, at least so far, these first ten minutes, and the character models look great too, as does the gorgeously revised backdrops.
Now, if you'll excuse me, I still got most of the adventure to replay! Onwards!
Edit:
OHHHH! Mystery Science Theatre! With Tim Shaffer! And Ron Gilbert! And Dave Grossman! I kid you not!!!

I'll probably get it when it's on sale for $2.50 or so.

I've missed you, Largo. Sort of.

I agree. While I want to support Monkey Island, I already own the original and would rather wait till this version goes on sale.

Game sucks!

Do tell. I myself find it mysteriously less sucking than you do, it seems.

The characters are look horrible but everything else in game is pretty good. Surprised they didn't make any diagonal walk cycles or even attempt lip syncing though.

I don't like Monkey Island. XD

THEN YOU MUST DIE A DEATH SO HORRIBLE AND PAINFUL THAT...
Eh, fair enough.

Seeing as this is the only Monkey Island I haven't invested any significant amount of time in, I pretty much had to jump on this one. So far, it seems to be a significant step up from the first remake. The animation is still inconsistent, but the art on the whole is more palatable (even pretty great at points), and the timing for the spoken dialogue is much more natural. As for the game itself, I'm still not far enough in to make any solid judgment, but it seems like a good time indeed.