Arbitrary reasons like the person that puts their own time and effort into developing the mod getting compensated? oh how horrible. The injustice of it all! How can a developer not give you what you're entitled to? After all, you've done so much for him right?
If you can't wait pay, like the old saying goes if you want to live like a king you need to pay like a king. Or learn to make your own mods. Than you'll be the one who gets to chose the arbitrary reasons.