T10/Greenwalt aren't the first, nor the last developer/head to say a game will have a feature that never comes. I know my buddy hates the fact that the youtube upload never came to GT5 nor that the damage/private lobbies patch mentioned for GT5P never came. They all do it to a degree. I think too many fanboys latched onto what T10/Greenwalt said on both sides of the fence, and made it much more than what it was. You can see this with them continuing the 'definitive' comment with FM4 since even negative press can be viewed as positive.
Forza 3 did not move the motorsport part to the background. The whole game is about motorsports and racing cars on tracks. Your career starts you off in easy races and your last year is the hardest with the most level playing field racing the fastest cars. The livery editor adds, not subtracts, like many other modes. What better way than to take any car in the game and slap a racing livery or theme to it, like the Gulf livery that many seem to like painting on just about every vehicle in the game sides with motorsports, not against it. The photo/video modes are an extension since you're taking photos/videos of the racing (there's no scenic views, it's either your garage or on the track). There's no museum section here either. List goes on but it's one of those..
Many of what people wanted was what was discussed/promoted more. T10 actually went to the people who like some of these features to make them better, and such publicized them even with promo videos. With all the enhancements and additions within a 2yr dev window some things didn't make the final cut like tourneys while others suffered like custom public lobbies. I'm sure T10 listened and will hopefully follow suit with FM4.