Yes, yes, yes, yes, it is important. Essential, crucial.
I don't even know where to begin, since I am a G-1 and can only procrastinate so much tonight. But, that said, some faculty move, go on sabbatical, have visa issues, family issues, took 2 students last year or none in the last 5 years, hate teaching or love teaching, think your work is fascinating enough to send an engaged response, or so boring that you get a 'good luck' with initials, and these are good things to know. It is also nice to know if your personality matches, as well as your research interests, since you are likely to know this person for the rest of your (academic) life.