If you purchase a DVD you own it. You keep it with your other DVDs in your DVD collection. You cannot collect movies purchased digitally through iTunes. It is not a physical item you can hold and technically you do not own it. You just have unlimited access to it on their terms.
So besides a movie that your kid(s) love and will watch hundreds of times without getting sick of it why do people purchase digital content?
Is it to see it without having to wait the week or two for it to become a rental?
Do people watch some movies repeatedly enough to justify purchasing them without actually owning them?
Am I just so cheap I refuse to purchase things so I can enjoy them repeatedly?
Too many questions