This is an interesting question because it involves weighing up the right balance between a business and user requirement decision.
You could almost argue that if some customers really want this and would be willing to pay for it, then you could implement different plans that might be costed based on usage or licence seats.
Without knowing too much more about the circumstances, it seems contradictory to cite economic/financial reasons not to charge for something that some customers really want if they are willing to pay for it. You still incur the cost for having to provide it to the customer, so why not try and validate the assumption of whether they are willing to pay for it?
Thinking further down the track, it is even more costly to provide a feature for free but have a service level agreement that requires you to maintain and update the feature. I suggest trying to avoid the complication and work out a business case that makes the feature (if not the product) more viable from a financial perspective.