Im not trying to fight with you, just offer a different perspective, and I think you should try to keep the comparisons equal.

styling: I think they did what they could with the time they had. It looks like a cavalier because they had to use the aerodynamic certification for the GP so they couldnt change much if anything. Hell if they couldnt even put hood scoops on it, they sure couldnt do much if anything else. Personally I think they should have taken the time and waited for a mid 2004 or 2005 intro and done everything they wanted to do.

Trunk: could you really fit clothes and 2 golf bags in the TA? Not without folding down the seats. and if you are going to do that, just toss a set of clubs or your clothes in the back seat of the GTO. Sure the vette has more trunk room but it doesnt have 4 seats. Same difference either way.
The trunk is small because of where they had to relocate the gas tank for US crash compliance. Its not like they did it on purpose. Honestly though I think they really need to do something about that. The lack of trunkspace is a big negative IMO. As is the lack of a sunroof. How the hell do you design a car for AUSTRALIA where its sunny and warm everywhere and NOT give it a sunroof.

1/4 Mile time: was that 13.3 stick or auto for the TA? Ive seen 13.4 at 108mph as the best 6 speed time for the GTO in more than 1 magazine. the 13.8 is usually for the Auto.

As far as skidpad, I think the tires they use on the GTO are a lot more "all season" than the TA, and they are narrower. Plus the GTO is prob tuned more for ride than the old Fbody was.

One thing I realize as I get older, when you are in your 20s or younger, .1 second in the 1/4 mile and .1G on the skidpad mean Everything. you will spend 1,500 bucks just to drop your 1/4 time by .2 seconds. You drive around looking for someone to race, someone to embarrass. Is that mustang faster than me, lets find out punk.
Thats why some people pay $900 for the total BMR suspension kit instead of $150 for the GMPP.

WHen you are 30+ and 40+, and you have a family etc, you really dont give a rats ass if the car runs 13.5 or 13.0, as long as its moderately comfortable, doesnt beat you up and is FUN to drive and you can take a kid or two somewhere in a pinch.

I think the GTO was/is intended for that 2nd crowd.