Yeah the pricing thing is a bit tiring, it's quite easy, if you don't like the price, don't buy it...
No the price reduction is not skewed in favor of people who don't own previous content, check the price for each content, remove the % discount for the pack and add it all up and you'll see exactly what you are supposed to pay...
The pack includes a LOT of liveries, which is why it costs you that much compared to just buying the car you're missing.
Now there's a subject I agree on being awful, charging money for liveries, I completely object towards it, I find it ridiculous! But instead of littering every thread on RD about it I have;
Voiced my opinion about this to Sector 3 on their official channels.
Opted to not buy all liveries, vote with the wallet.
At the end of the day I support S3 with my cash because I like the sim, if theres something I don't like I make sure to post it over at their forums.