Didn't FM2 and 3 also have a lot of updates, and didn't they also tend to introduce more problems. Isn't that how the AWD glitch was introduced in FM3?
I don't know. You can either take a lot of patching as a sign that the game was unfinished, or you can take it as the developers are still listening to the community and trying to make the game better.
I do agree, that there wasn't a lot of stuff to do in GT5's career. But to me, the careers on both game are kinda even simply because what FM4 makes up in number of events it fails at the variety of tracks. That's why I thought Forza 4 had less real world tracks. FM4 doesn't use them that much. (Also, I only did the Miata endurance once in GT5. I don't fully understand what you were getting at there. Are you trying to say you race the miata on Tsukuba a lot? But there's the endurance and maybe another race there with it? Which pales in comparison to ho many times I've gone around the Alps in FM4...or Sadona in FM3. (both tracks I HATE now.)
Speaking of tracks, I should have mentioned that the track models in GT are better than FM4, in my opinion.
As for the Autovista cars being a representation of the future, maybe. As for them being driveable, Ha ha, no. Sadly, the Autovista cars, the menu car and the car you actually race...are not the same car. Sorry. The Autovista cars are all laser scanned and incredibly detailed. (Except for maybe the Warthog. They COULD have laser scanned one of the movie prop ones, but it's more likely 343 gave them their in-game data and T10 tweaked it for FM4. Still wish that thing was driveable.) The menu cars are obviously higher resolution than the actual driveable cars. Think of the cars you race as the Standard versions of the Autovista cars.
I also want to say that Seasonal Events and Rivals aren't quite the same thing. I guess you could argue they serve the same purpose, but that's even a stretch since Seasonal Events are mainly a way to earn money and experience outside of the main career, and while Rivals do that, too, they're mainly just for fun 'cause you can still earn plenty of money racing around.
I guess I see your point about the raised level cap...but...I don't know.
I don't count the Auction House as a pro, 'cause I don't find much point of it anymore with the Storefront. With the storefront you can buy the liveries and tuning jobs you want without wasting a lot of money on a car.
Also, I don't quite like some of the prize cars they give you in the levels. I've said this before about Forza, but there's one level where they give you a choice of one of five most expensive cars in the game. And the only problem with that is...it kinda makes them worthless. I guess, by offering a choice it doesn't TOTALLY kill the value except most people are going to pick the 9 million credit car over the other two because they don't want to spend that much.
Neither game is perfect by far. And I doubt GT6 and FM5 will be perfect either....Let's just say I don't fully understand some of Turn 10's choices. GT5 is a massive game that took too long to make and cost a lot of money. FM4 took two years to make, so I guess you could argue that there wasn't a lot of time for them to make better decisions, but there's really no excuse for bad decisions. If you know you don't have time to finish a game, then either don't release it, or do what PD has done a few times in the past and take out anything that's not fully complete and release it. (BTW, I believe with GT2, GT3 and GT5 PD was under pressure from Sony to release the game despite it not being fully completed. I can't really mark a game down for not being complete when it wasn't entirely their fault it wasn't complete.)
EDIT: As for T10 fixing PI issues...umm...hasn't EVERY Forza game had an issue with some car's PI? I believe so. Which, you'd think they'd learn their lesson after four games, but I guess not.