It's most likely a change that has to do with Blizzard's attempt to lessen the ""grind""-feel of reputations. Many repeatable quests have gotten reputation boosts, this one included.

As of patch 2.2 this now gives 500 rep.

Quick math!

Each Twilight kill grants 10 CC rep. Assuming you are Friendly (0/6000 towards honored), that means you require 39000 rep total to get to exalted (6k to Honored, 12k to Revered, 21k to Exalted).

39k/10 per mob = 3.9k Twilight Kills.

Each Twilight has ~30% chance to drop a text. Text turn-ins (groups of 10) are worth 500 rep. Thus, every 100 kills will yield you an average of 30 texts, worth 3x500 (1500) more rep. If you were to *actually* kill 3.9k Twilights, you'd get (based on probability) around 1300 texts, which is 130 turn-ins for another 65k (!) rep, far more than you'd need TOTAL for exalted status.

...or, to make it even easier, 1 mob = 10 rep + a 30% chance at 50 rep (as per 10 text/500 rep = 1 text/50 rep). 50 x 30% = around 17 rep (rounded), so we'll simply state that 1 Twilight = 27 rep (avg).

39k/27 rep per mob = 1444.4 (say 1445 for simplicity).

Even further, every Twilight that you come across has a 5% chance at dropping Cultist Gear, of which there are 3 pieces:
https://vanillawowdb.com/?item=20408 Twilight Cultist Cowl
https://vanillawowdb.com/?item=20406 Twilight Cultist Mantle
https://vanillawowdb.com/?item=20407 Twilight Cultist Robe
These are, in turn, donned so as to use the Lesser Wind Crystals https://vanillawowdb.com/?npc=15211 to https://vanillawowdb.com/?npc=15212 summon https://vanillawowdb.com/?npc=15209 an https://vanillawowdb.com/?npc=15307 Abyssal. Killing the abyssal will yield an https://vanillawowdb.com/?item=20513 Abyssal Crest. (Pathetically easy these days, too, as they have the same HP as the Twilights around them) Collecting 3 https://vanillawowdb.com/?item=20513 Crests allows for another turn-in, this one yielding 150 rep, or 50 rep per https://vanillawowdb.com/?item=20513 Crest.

So each Twilight = 5% chance of 1 of the 3 Cultist set-pieces. Out of the same 100 kills, you'll get 5 pieces, barely enough for 1 set (assuming that they're not all the same -- i.e., 5 cowls, 4 mantles and a robe, et cetera). A negligible increase in rep-production, but seeing as how it's a fine thing to do while waiting on respawns (and the fact that they Abyssals drop various other items, including high-end pre-BC greens/blues), it's better than nothing.

So out of our current number of 1445, you could be expected to see 289 set-pieces dropping. RNG on your side, that's 96 Summons, granting you 96 Crests and 32 turn-ins for an additional 4800 rep. Once again, though, that would push over the amount we're shooting for, so you wouldn't need the full 1445 kills to get to exalted. Assuming a more flat-number of 1300, you would receive an average of 260 pieces, or roughly 86 sets (assuming no duplicates -- yeah, right, I know). That's 86 more crests, which is 4200 additional rep. 4200 Rep / 1300 Twilights = 3.23 rep per kill.

So.....

1300 Twilights = 10 per kill, 30% chance of a text (~50 rep per), 5% chance at a cultist outfit. Averaged Rep per Twilight = 30.

So you have a definitive goal to set for yourself in terms of numbers to kill in order to hit exalted; simply calculate how much rep you need and divide the number by 30 and you'll reach an approximate number of Cultists you need to slap around. And, frankly, since the Cultist outfits aren't controllable as to which one you'll get (you could grind for ours and theoretically never see a Cowl, only Mantles and Robes), It's easier to rule them out and simply grind on the 27-mark (or the aforementioned 1445).

Note -- I realize there are quests that yield CC rep, as well as running AQ20 for rep-per-kill and the various daily quests and turn-ins you can do all through Silithus. In addition, I'm not counting Human rep-gains (+10% to rep, so enjoy your faster farming) or the higher-end summons (that require turning Crests and Large Brilliant Shards into Necklaces and Signets to summon 5-man/20-man bosses), as they take more time and effort than simply chowing down on more hapless Cultists. I wrote this simply from a grinding-standpoint, which I firmly believe would be leagues faster than any questing you could attempt (especially at higher-levels). That, not to mention the runecloth/cash/drops you'll receive, makes grinding Twilights a FAR more attractive idea to me than runnin' all over, carrying SIlithid goo or killing elites. For people such as myself that never did finish our CC rep-grind, this is a VERY manageable and profitable method to attain Exalted Status!

This quest gives 500 rep with Cenarion Circle (not 250 as it says in the text)