How fair is "marketing promise" being broken as criticsm?

I used the term "marketing promises" because that's what they, promises with marketing purpose.

Scenarios:

• A developer promises that certain features only for the final release either not having them or being toned down.
• A developer shows some features in trailer(s) only for some/many of them being missing or toned down.

To some this is an issue (of varying degree of annoyance), one that merits being listed as a shortcomming of the product.

To people that have this view, I'd like to know why do you put such weight on that?

marketing promises are how expectations are shaped, and when those expectations arent met in the end it leads to dissapointment.

i think its valid to complain about it but some players use it as a reason to trash the entire game (like it happens with FFXV) and thats when it becomes empty hyperbole...

I don't think "breaking marketing promises" is necessarily an invalid point of view, but it is something I firmly believe has no point in (consumer-oriented) criticism which should be organized around the final result first and foremost. Where it has merit, I believe, is in examining it in the context of a "post-mortem", i.e. pieces that examine hype culture surrounding a game because it may help explaining why certain aspects turned out in a particular fashion.

Every time developers show off things still in development they always say things like "subject to change" or "still in development". Yet, every time, people get disappointed when things don't meet their expectations or things get changed over time. Gamers are ungrateful and selfish many a time and don't think about the implications of things.

If something is cut from the game or things change during development, that's to be expected. Crying about it just makes people look entitled.

As for me, unfulfilled marketing promises are bad form first of all. But everything can happen especially if we are talking about programming and game development. A deficit of resources such as money and knowledge may cause unfulfilling. Only experienced developers know what they are able to do and which things won't be done anyway.

It's better to think about the final results and don't mention promises in the process of game evaluation. But unfulfilled promises undermines our trust and we are not going to believe the developer next time.