Feature creep is term that came from software development where it was used to describe software that over-emphasizes new features at the expense of core functionality and design imperatives.
It contravenes the primary rule of the Unix philosophy for writing programs:
do one thing and do it well
But it has spread outside of software and is most encountered in technology products that build in so many features it actually makes the products harder to use.
It's a symptom of the paradox of choice - people think they want loads of features, because we think we like choice, but actually we hate it.
As James "Wisdom of Crowds" Surowiecki points out:
The strange truth about feature creep is that even when you give consumers what they want they can still end up hating you for it.
The solution is not to give consumers what they think they want:
We don't ask consumers what they want. They don't know. Instead we apply our brainpower to what they need, and will want, and make sure we're there, ready.
Akio Morita, Founder of Sony