While I think programmers for whom programming is a "passion" (and often have lots of side projects and involvement in programming generally outside their work) can be among the best, I've also met tons of excellent programmers who approached it mostly as a profession and weren't really involved much outside of that. I've also met some really awful programmers who were "passionate" about it as a hobby.

Passion outside of work is neither necessary nor sufficient.

[I, personally, am of the "passion" sort. I find that this attribute can be both an (obvious) help but oddly, also sometimes a hindrance, as I can get too personally involved in things, and sometimes that clouds my judgment.]