User control and user happiness

How much control should our users have? -- so asks Kathy Sierra at Creating Passionate Users.  The conclusion: users need control, but not too much control--which results in the same negative results as not too much control does.  Sierra writes:

We shut down when we're faced with too many choices, even when those choices are about relatively simple things.

How does this apply to library services?  All sorts of ways... 

We should have library account access online that lets users customize certain things: the way they get notices, what they get notices of, what their landing page looks like...  Should we stop there or keep going?

We should let users customize their experiences when they access our online library resources too--but again, how much?

Interesting questions to ponder...