Unless DLCs that cost money were being duped and traded to other people, then no. Duping never cost PD one cent, whether people were charging each other for it or not. I never did it, might have considered it, but probably not. But it wasn't hurting anything unless it somehow hurts someone to have people able to get all of the cars they wanted in less than 4 years without running the indy 500 seven thousand times.
But anyway, glitching and duping is a stupid argument that I could care less about.
Saves for endurance races are a must, especially without the option to let BOB drive for a stint or two while you nap/eat/barf/whatever. I like doing endurance races but no way could I ever hope to do more than the 9 hours of boring pointlessness... err I mean Tsukuba, in one day. And if I'm going to leave a game on while I sleep so I can run a 24 hour race... it will be rFactor, not GT with 4 cars on a giant track that all park if you pull alongside them.
The second thing that is a must is an ability to save your setups. It's completely unforgivable that you can't permanently store a setup that you may have spent weeks perfecting. On top of this, if you absent mindedly change your upgrades it loses whatever changes you had made to suspension or gears or whatever you just changed. I should be able to put the stock tranny in for one race without having to completely re-create my gearings from scratch when I put the full custom back in. Ridiculous.
And third... fix that stupid AI parking thing so I can use a car that is a little bit closer to their performance please.