Had I backed Phoenix Point based on what was shown in the Fig pitch, I wouldn't have been happy with the result either.

I just skimmed the pitch and it seems pretty close to the final game. What am I missing ?

For a first, all the visual style that got changed between the concept art and models shown in the pitch; especially since the devs then spent close to a year on this without communicating with their backers. And especially since they most likely used their improved graphics to secure the deal with Microsoft, instead on focusing their effort on fulfilling their promises on gameplay features, many which are missing from the current game.

I don't think that a pitch is any kind of promise about what will be included in the game.

Features often need to be cut, e.g. because they sound good on paper but just don't work in practice.

For me, I expected something more closer to the classic XCom games from the 90s. What I got feels more like a spin-off of the contemporary X-COM games, with interface, camera and general gameplay cloned 1:1.

As someone who's never tried the classic xcom games what's the main selling point for how that's better?

I don't think the older games are necessarily better. But they are different and the pitch gave the impression that the intended product would be closer to X-Com than XCOM.