That's true. I feel there's another point. S397 need to produce content at a high rate, since other sim's have more official content. For that reason I bought the Formula E and Hong Kong. I've driven that car maybe for 2 hours, so money-wise it was expensive, but it helps S397 develop our beloved sim and for me that was enough to buy that specific DLC.
The other content (GT3 pack, endurance pack, Sebring laser scanned) I really wanted to buy. The price for Sebring is high, but I feel that average prices will go down at S397 in the future, even for new releases, because they'll have more experience with e.g. developing a laserscanned track and a bigger crow to sell to. A lot of people fell out of love with rF2 due to the ISI development issues. S397 is making up for that big time.
Personally I would love if they sold all the items individually or at least tracks and cars separately.