As they should. Grandfathered gear that makes for interesting choices compared to modern options, adds flavor and swag to a given bracket. Grandfathered anything that makes a bracket lopsided against non-grandfathered players or creates a wild upset in the impact of stats in a given bracket, essentially nukes that bracket. Blizzard's going to overlook things like this, and it's up to enthusiast communities like this one to manage the health and expectations of the community. I have no sympathy for twinks who hide behind "but anyone could have gotten it" excuses for problematic aspects of the game (not aiming at you,
@shanker ; you brought up an important point in this thread, and I'm expanding on it).
My favorite upcoming example in SL: SL 19s can attain 100% mount speed by leveling to 40 before the prepatch, attaining the 100% mount speed, then landing eventually at 19 in SL. If Blizzard fails to put a level requirement or some other disabler on that ability (or fails to give everyone 100% mount speed at 19), then one of the two non-ftp/vet XP-off brackets that received the most interest in the last couple of months goes dead on arrival. Who's gonna roll up a new 19 or update an old 19 with a 40% mount speed disadvantage?
Necessary nerfs like bandages in cata, big daddies and bolt guns in cata, and the list
@shanker put together get relatively quick attention from Blizzard. Subtle issues like the Cata queue bug that destroyed games for only the 60 bracket for four months, or single item oversights like fishing pole damage, or grandfathered enchantments in cata...those remain up to communities like this to point out. That's part of why guides like the one that started this thread are so important. Not only do they bring old and new players up to speed, but they also serve to publicize issues that can hold back a bracket.
Notice how Cata easily brought the majority of issues of any expansion in WoW? SL looks to overtake Cata in the sheer impact (and number of oversights) for XP-off play. Yes, it's hilarious that honor gems haven't been scaled yet. It's not hilarious when people decide not to play what could have been an otherwise popular bracket in SL because there's no point. Why PvP when everyone gets one shot? Why run a dungeon as a newbie when some other player of the same level inexplicably bulldozes the whole dungeon on their own, leaving the other four to scratch their heads?
I get that there's a subsection of XP-off players who enjoy lording gear and stat advantages over other players. That's part of twinking, and I respect the work that goes into finding and obtaining gear and stat advantages. When that pursuit breaks games because the advantages eliminate swaths of interested players or the advantages are not available to players willing to do the work but who happened to miss a particular window of opportunity, then we need to "bone our own". At the very least, more of our own will want to play, and at the very best, we make a positive impact for WoW players as a whole.