Seems to me you either do it, or you don't...no?
A similar situation perhaps - a lot of high end professional photographers like to retain the rights to the negatives (or in modern day, the high quality original digital files) so that they can continue to make money from you down the road if you want more copies, enlargements, etc. To buy the rights outright costs a lot more - IE, they get their money upfront. We bought our wedding photo negatives outright for this very reason.
So, long story short...maybe agree to their terms but tell them it'll cost them more for your services as a result.
But then again, knowing what I know about coding (I have a few friends who are career coders), it seems to be getting increasingly cutthroat - too many terms or restrictions on ones work and the contractor just moves onto someone else who will bend to their whims and desires instead.