20.10
It’s obviously unethical to break something that others depend on in order to gain wring extra profit out of them. There are interesting cases of developers breaking their products to protest the system or stick it to the man or something, but this is not one of those lofty cases. The more interesting question is whether it is useful or profitable in the long-run to conduct.
Someone in the company concerned with quarterly profits and the current stock price might argue the ethical or at least fidusciarily responsible decision is to modify the interfaces to coerce the customers into spending more money, but I doubt that this would increase profitability in the long run except under two probably rare circumstances. The reason I doubt this would work in the long run is that if the customer ever discovers what is happening and has the ability to change vendors, they most certainly will do so. That 2nd quarter spike in profits results in a loss of a valuable customer that puts a dent in the next 8 quarters. The two circumstances under which it might be a net gain to do this sort of thing is if the life cycle of the product is so short that the customer never has time to figure out what’s going on or of they have no other options to replace you. I suppose that software life cycles are often much shorter than the life cycles of hard systems, and the service you are providing to the customer might be obsolete fairly quickly, but at the same time the software landscape is quite competitive and a replacement is likely right across the street.
Anyway, the unethical nature of this business decision is pretty straightforward, and I think the business utility of this sort of behavior is under most circumstances pretty weak.