Nay. Yes, they may be ugly. So what? It's a game. If people want to ruin their cars...
Me personally, even in NFS, little as I've played these late games, I still always likes the stock body best of all.
Why not do both? You don't have Atari design the bodykits? Trust it to the community! Give the game a proper plug-in system like in Fallout 3. Well, hoping for GECK is too much, but at least make a simple tool for players to stuff their bodykit into an in-game shop and release it. And then let anyone design as many body kits as they want.
[ In online games, this might increase server load, but that's easily solved by only loading bodykits on cars than are near you - or, better even, introducing a peer-to-peer connection for this data. And only if the player turns the option on. ]
There's some stuff that requires professionals, such as coding, and a lot more that doesn't. Not just custom challenges, but models and textures. And a lot more.
That's not the most important bit. This is just a minute inaccuracy.
The biggest letdown in TDU for me is physics engine itself. It's not just that it's unrealistic, rather it's unrealistic and not fun.
Try and play NFS Porsche Unleashed. Yes, the physics aren't super-realistic, but it's just the feel of the thing. It feels absolutely mechanical. You can feel the wheels, how they are touching the road, how good the road is, how much grip do you have. You can feel the car's engine and transmission. On the screen, the car actually tilts in turns, depending on how stiff the suspension is, and the weight shift affects everything. The tires and the brakes squeal in hard corners, and you feel it through the wheel as well. You can almost play it blindfolded, for you can always tell what car you're driving and at what speed just through the wheel. You don't doubt for a moment that there's a real rack and pinion in front of you.
A minute drawback is that with the exception of a few tracks, the road is always dry and the tires are apparently soft (not the stock kind, but quality performance road tires), but can you call it a drawback even? It's loads of fun, it's more fun even than rFactor or Dirt.
In TDU, it feels like you're driving a hovercraft. There's no grip at all. IRL, if you turn the wheels to the lock and step on the throttle, you make a bit rough U-turn. In TDU, the vehicle just spins out in a cloud of smoke. IRL, the car only lets go after you overstep the limit. In TDU, it seems to be hydroplaning all the time. Negotiating corners is no fun, it's solely a matter of braking enough before entering the corner - playing with throttle and brakes through it is pointless.
High-speed driving is even worse. IRL cars keep their direction very strongly, you need to wrestle them away from it, while in TDU they're just waiting for a finger touch to the wheel to turn 45 degrees. And it's better not to mention the force feedback, what is it connected to - a randomizer?
Of course, it's nowhere as terrible as Need For Speed (any other than Porsche Unleashed), but being better than that is not much of an achievement.
Really, if they just fix the physics, it won't be a game any longer - it will be a drug.
[mod edit:] Please do not double post, use the edit button, thanks!