I'm of the opinion that once a band has broken up, it should never reform. Since, as far as I can tell, most times bands reform, it is without key members, and as such, they are basically nothing more than a tribute act. Or, the band members have moved on musically since the group broke up, and the material is so different people will split up the records into two eras, the good, early stuff, and the bad, late stuff.
But that's just my opinion and I tend to make stuff up based on ridiculous generalizations, and as such I am probably wrong.
That said, I am also of the generation of people who will never get to see Fugazi live, and this disappoints me greatly. I would also like to see a pre-GNFPWLBN Modest Mouse gig, a Walkyier-era Skyclad, Neutral Milk Hotel.