The Changes
Getting a character at revered reputation with a given faction qualifies characters on your account to receive double the normal reputation. The character who unlocks the bonus is immediately included for their advancement from revered to exalted, which works out to fully 25% of the old trek from neutral to exalted since the last stage is the longest. Additional characters on your account - supposedly including all servers and all accounts on your Battle.net account, though I'm unclear how this works cross-faction - will see doubled rep for an effective 50% reduction in requirements.
To put the numbers in chart context:
| Change To Rep Gain After 1 Character Hits Revered | ||
|---|---|---|
| Rep Level | Current Rep Per Level | After qualifying |
| Friendly | 3000 (~12 quests) | 1500 (x2, ~6 quests) |
| Honored | 6000 (~24 quests) | 3000 (x2, ~12 quests) |
| Revered | 12000 (~48 quests) | 6000 (x2, ~24 quests) |
| Exalted | 21000 (~84 quests) No longer ever required | 10500 (x2, ~41 quests) Includes 1st character |
| Quest estimate assumes 250 rep/quest, not counting bonuses (guild, human racial) | ||
History of the dual role
We've seen Blizzard struggle with this sort of thing since the use of rep grinds became increasingly common in the Burning Crusade. Prior to WoW's first expansion, reputations were used - sparingly - for certain rewards, but these things tended to be specific items you obtained and could skip if you had some other source for comparable/better stuff. In general, it has been accepted that additional characters have to obtain their own gear somehow, and I don't recall that much outcry on the fate that befalls additional characters needing to repeat the same reputation grinds.
WoW's expansions slowly increased the use of reputation to gate things that were less optional - TBC controversially required revered reputation (later lowered to honored) with four separate factions for access to heroic dungeons (which were then required to complete quests for access to raid content). More significantly, WoW's first three expansions pushed the use of daily-quest based soloable rep grinds as a way to gate access to enchantment options for specific armor slots (head, shoulders).
The latter change mattered because - unlike gear that you will eventually replace - the rewards were not skippable. Everyone had to complete the relevant daily quest grind or they would be unable to enchant their gear. Late in the Wrath era - and continuing with Cataclysm, Blizzard decided to make these items account-bound. This alleviated portions of the problem, but you still had to grind each daily quest faction once per account.
Why now?
Blizzard elected to remove head enchants from the game entirely rather than continue this trend and/or re-introducing them elsewhere - high end shoulder enchants are also gone from rep vendors, and are now produced with the Inscription profession. Unfortunately, Blizzard created other issues to replace these.
Pandaria expands Justice and Valor points beyond the traditional group content of past expansions, and Blizzard opted to use rep restrictions to gate access to this gear. In years past, this would have been relatively optional, but the dungeon finder has made item level checks mandatory. This became especially prohibitive for players needing to get multiple characters up to par. Spreading the entry level gear amongst four factions does not seem terribly consistent with the design of removing enchantments from vendors to make them more optional.
On one hand, it seems unlikely that the changes go far further than the immediate problem by accident. The effects on players grinding rep on a single character are significant, at a time when Blizzard was pushing to make the rewards for getting to exalted less significant and more cosmetic. Based on the scope of the fix, perhaps Blizzard felt the length of the rep grind ladder was a deterrent, especially with increased numbers of reps in Pandaria.
That said, it seems counterproductive to reduce the amount of repeatable content in the game for people who like repeating daily quests solely to fix an avoidable issue with gear vendors. Perhaps the daily quest isn't going over as well as Blizzard had hoped, but that too is a weird and potentially troubling circumstance with all of the investment they made in daily quests this expansion.