Don't be a pissant, just complain about the price and length like everyone else so that you won't seem so salty. Right now you seem very transparent, especially when everything you complained about can be turned off with a switch of difficulty.

How many other examples apart from Bravely Default can you list? A demo is a small part of the main game given for free. Simple as that. Bravely Default is the/an exception. 

As for the average gamer, of course it will take closer to 1.5-2 hours to complete. I never said that it would take the average gamer 5h to beat it. What I'm saying is, using a speed run to call this a 10 minute game is actually even more ridiculous than to say that it's a 5 hour game. In the first case you're not playing the game, in the second you play everything. Both unlikely, with the former being less likely than the latter. 

That's ridiculous, Kojima done lost his shit.

The Zelda demos for Skyward Sword at E3 were not a part of the main game, the Aliens: CM demo wasn't really part of the main game, the SOMA trailer won't be a part of the main game...its not really something you can search for though so that is just off of the top of my head
Its not horribly uncommon for a game to create content for a demo, whether it is released to the public or at an event...either way, selling a game that is this short for 30$ is robbery.

If you are uncomfortable calling it a demo, then just think of it as a piece of the game that they cut off just so they could sell it separately...I personally don't think that selling a game that the average gamer will beat in 1.5 hours is something to be defended...

What if you considered it as DLC that you bought before the game?

First of all, thanks for the examples. I haven't played them to know if their content matches the content of Ground Zeroes, but still. Robbery is still a strong word. No one is forcing anyone to buy this game at full price. If you want to teach the company anything, wait till the price drops to an amount that you believe the game should have cost in the first place. 

As for whether this was a part of the main game, well we don't know. I didn't see gamers getting upset with the GT prologue games and I'm sure they cost quite a bit (GT5 sold 5m despite that). Kojima claims that the main game is very long, so they could have easily cut it shorter and released G.Z. as dlc and then more DLC from parts of the main game. If the game is indeed long, then I think it's unreasonable to demand to include it in the main game. The way I see this is as an overpriced dlc with a retail release. By the time MGS5 releases, I'm sure it will cost as much as any other dlc. 

Super Mario Bros can be beaten in under 5 minutes. OOT in under 19, Half Life in half an hour and Gone Home in 14 seconds. Length of the game determined by a speed run doesn't mean anything, just sit back and enjoy the game. If you feel strongly that Kojima is robbing you then don't buy the game, no one is conscripting you to buy it.

And then they give it 9/10 with this

Ground Zeroes is a joyous tangle of toys jostling around in a well-formed sandbox, and the various side missions that sit separately from the main campaign take great pleasure in pushing you to explore and exploit them. They're a playful bunch, revelling in emergent action that unravels in often unpredictable ways. Spend eight hours dabbling with Ground Zeros' playground and it will still find so many ways to surprise you.

Speedrun of the main mission doesn't mean much.

Gone Home can be beaten in under one minute. Didn't stop people from thinking it was one of the best games of the year.

At least Ground Zeroes is an actual game.