creeping featurism
n. The tendency for complex systems to become even more complex over time due to the constant addition of new features.
Examples
2003
Features sell. Long ago, Microsoft recognized that features sell software not code size, efficiency, or even a pretty interface. Features. In the old days of software competition, to compete with Microsoft, you would put up a features chart and a side by side comparison of your product to the Microsoft offering. When your product was faster, you'd sell speed as a feature. Microsoft would counter by copying the same features and combining them with those of another competitor's product. Nobody could match Microsoft for adding features. And when Microsoft couldn't add features, it would say it added them and just not implement them, knowing people were buying software based on the claimed features, not on any real usefulness of these features.

In the 1980s, the term creeping featurism was coined. It's now become part of the landscape.
—John C. Dvorak, “Microsoft, Innovation, and Linux,” PC Magazine, January 01, 2003
1997
The tendency for fancy software add-ons, called "creeping featurism", is also a hidden menace. The more functions a program boasts, the harder it is for a user to find the one he or she needs.
—Anjana Ahuja, “A price we must pay for progress,” The Times, June 18, 1997
1984 (earliest)
Since mainframes have been around longer, the software development process has been fairly well defined.

On the other hand, micro software is often written on the fly. For micros, "the process used in development is pretty crude," Miller said.

He calls the phenomenon "creeping featurism." The program's originators start out with one objective and end up tacking on more features as the program is written.
—Avery Jenkins, “In search of PC software standards,” PC Week, October 23, 1984
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