I don't know if it's applicable to everyone - as there are companies which produces infertile seeds* - but you are right about the fact that many applications of GMO are for increasing the product yield, therefore decreasing world hunger.

*: I live in Turkey, many types of imported seeds are sold here and they are engineered to be infertile. For example, you have an imported tomato seed. You plant it and you get your tomato, right? And normally you can use some of the seeds from your new tomatoes to keep producing tomato, but with these engineered seeds the tomatoes grow up seedless or with infertile seeds I suppose. So you become dependent to seed selling companies, etc. Long story short, not every engineered organism is modified with benevolence in mind.