I did not know that all your games are perfect

.... I doubt any game is entirely "perfect" especially Forza 4 because there are a similar amount of comprises to be made.
In fact I will challenge you, name something in Forza 4 that does not have any compromises.
Similar? No... not by any stretch of the imagination... GT5 was the first game to ever split content up in premium and standard for cars (and to an extent, the tracks).. And to have such a long list of features not consistent throughout the game, even after many were patched up. Folks harp on dynamic time of day and don't realize it's only present on 3 tracks (Toscana-fictional and 2 real tracks- LeMans and Nurburgring's Nordschleife) and sadly the DLC track, Spa, didn't get this cool time shift. Weather is present on 8 tracks (9 if you count Spa). 80% of cars can not go into photo travel. 80% of cars can not get wheel upgrades (not that it matters because it's visual upgrade only) amongst others. 80% of cars originally did not have the cockpit view at all and now most have just a black silhouette. Even after being patched in, 80% of the cars in the rain do not have working wipers and the 'cool' splash effects you get in weather on a premium are not there when racing in a standard. Damage is specific to what mode you are in, not in career modes nor seasonal events and visually is dependent on the car you are driving (frankly, not done well at all in the game). You get 19 racemods in the 1000+ car list by default, and PD charged you $8 for 11 more racemods (with 4 bonus 'new' cars via tweaks to a fictional 'superman' car (x2011) and 3 more fictional Karts). PD's idea of DLC is another slap to the face... $2 for 100 one time use paintchips, $3 for more racesuits and helmets

When you race with weather you get more screen tearing, frame rate drops, and last gen pixelation. Sadly, when all the stars are aligned, in a proper 'premium' HD track, in a premium car, or taking photos of premium cars in photo travel, NOTHING looks as good as GT5 is. Sadly the norm is when the stars DON'T align. I can keep going on and on but will stop here. GT5 is the definition of inconsistency and compromise. Maybe PD should have focused on their core business, game development, and not mismanaged resources taking on so many non-game developing projects while not expanding the PD team nor outsourcing any work
You got one thing right though, no game is 'perfect'. Had PD focused on premium content ONLY and making features consistent throughout the game you would not see the vast majority of complaints about GT5 and it's faults throughout. People need to accept it, like I accept that T10 has not implemented offroad tracks, dynamic time shift and weather. Or that some cars continue carrying over bugs from previous Forza games (not like GT5 is innocent of that either!) The
only thing you can peg as not being consistent in Forza 4 is AutoVista mode having only 5% of the game's car content.
FYI, I love both GT and Forza franchises and to me Forza has had the edge since FM1 launched after GT4.