Martin Fowler has posted a nice article on humane interface design (as opposed to minimal interface design). I am definitely on the side of right and good (read: humane interfaces) in this debate. Nothing takes the fun out of programming faster than having to write a bit of code that you know has already been written a bazillion times.
Minimal interfaces shift the maintenance burden to the clients. This is great for the library writer because they have less to maintain, but it is devastating for the community. Humane interfaces have the extra behavior because clients need them.
This is made worse by the fact that a well designed minimal interface requires fairly small amounts of addition code to implement each individual bit of common behavior. The fact that each of these common behaviors can be implemented quite easily means that they rarely get packaged and reused. For example, you are probably not going to add a dependency to Jakarta Commons IO to your project just to get
RegexFilenameFilter, you will just implement it yourself because “it’s only 5-10 lines of code” even though someone has already packaged it for you. And you are definitely not going to package and publish that useful 10-15 line utility you wrote last week because cost far outweighs the value of that one utility. Each of those decisions are reasonable in isolation but put together pretty soon you and your community are stuck with a lot more code to maintain than if that behavior had been included in the core library to start with. (See: boiled frog syndrome)