To resurrect this thread: this minions change makes no sense as presented. I can see why WotC might not want to errata all of the existing minions (though they've been using errata a lot recently).
However, once you have an XP system for balancing encounters, you can't ignore it in favor of "count minions less when planning the difficulty of combat at higher tiers." If WotC feels that minions should be worth a fifth of a monster at Paragon and a sixth at epic, their XP values need to reflect that. What if you don't get DMG 2 and just go by Monster Manual 2's XP values for minions? You won't build encounters appropriately, if 6-1 at epic is the intended ratio.
There's a thread in the WotC errata forums on this, and the response there doesn't seem too encouraging on this score:
here.