If they decide to drop the price someday, they'll be able to make all those sales too.
I'm sure they know what's best for their business and price accordingly, but personally the only software I own from them is OmniFocus. The reason I haven't bought more is nothing special--cost vs. utility. I'd love to use more of their stuff to enhance blog posts or presentations, but I don't see it happening their $50+ prices unless I have some very specific business purpose or I have a lot more disposable income.