When you come in defense of GT5's tracklist, consider that this is the biggest ever racing game release, nothing in the last 10 years has been as big as this release. It is also one of the biggest game releases in general for the console market, the ammount of money and time that has been put into this game is massive.
There is no excuse for it going backwards in terms of content provided. The trend with the games is like this, but the time frame was decent to warrent it.
GT - 1997 - The start of the series, it was great, a decent ammount of content but obviously a work in progress for something bigger, this paved the way for the future.
GT2 - 1999 - A huge increase in content in cars and tracks, this game was a masterpiece of a sequal, a big step forward.
GT3 - 2001 - New console and a small time frame to put out a game on a new platform, it had less content than GT2, less cars but it was good for the time it took and it did include many steps forward and new tracks.
GT4 - 2004 - A massive leap forward, a massive ammount of content and in general this game is a masterpiece, it raised the bar for the future, obviously taking from GT3 as a platform builder.
GT5 - 2010 - a 6 year gap, in old times this is the time difference between 2-3 game releases, GT5 is coming out at the time where we all probably expected GT6, and thus with that time investment we would expect, and should expect everything that GT4 offered, and a lot more, but in the 6 year time frame they have essencially done the same as what they did between GT2 and GT3.
Its a big dissapointment to me seeing how many of the old GT4 tracks (infineon?...) that have just disapeared, and to me night racing and fancy eye candy is less important than the content available. Its cool that they have the top gear test track, but it isnt a racing track, real racing could never take place there due to safety as it is a figure of 8, they could have spent that time doing silverstone which is a much better track, or spa which is one of the most legendary and exciting circuits in the world.
It amazes me that after 6 years this game is still not really complete.