I agree on the nickel and dimeing, but that is a matter of implementation.
Imagine In-app purchase options for options X, Y, an Z, $0.99 each. I only use X, so I'm only going to buy that. You use all the features though, so the developer provides an In-App option for all three features for $1.99.
Yes. To put it bluntly, when I see features priced that way it looks like artificial price inflation to get more money. Especially in software that already has a purchase price.
I would much rather pay the 20$ or whatever to upgrade my software, than be nickel and dimed all over the place.