On one hand I usually dislike how "play times" are often "rushing through the main quest, skipping all dialog, doing only what is mandatory to get to the end". That isn't play time, that's a speed run. At very least have the thing inclusive of all gameplay and cutscenes before giving a time figure. On the other hand, I do feel that for $40 I expect a full-length game. Games like Dear Ester and Journey often cost less than $10. If this is an introductory "demo/tutorial" , price it accordingly - $10, or certainly no more than $20.
What is more frustrating to me is that it appears that both Ground Zeroes and The Phantom Pain won't be released on PC, my platform of choice, at least in parity with the other consoles. I had hoped that, much like Capcom, Konami had finally figured out that the PC (especially released via Steam, or utilizing Steamworks) is a viable platform and there are lots of gamers that want to enjoy your products but have no interest purchasing a console. When they launched Metal Gear Rising: Revengance on PC with all DLC included, at an excellent price point ($20 for the first week or pre orders, $30 after that), I went out of my way to preorder and support it. So did many others apparently, as it was deemed a successful release!
Especially in this day and age where major consoles are basically proprietary, locked down, (and depending on your perspective, overpriced and underpowered) gaming PCs, I see no reason not to release for PC users from a technical standpoint and even less so to deny this valuable market from a financial standpoint.