It's worth keeping in mind (and this is aimed at Dev's, want to be Dev's and such... except you CCP you can just keep going LALALALA in the corner becuase we went blue in the face trying to explain it to you) that WoW is the exception rather than the rule when it comes to subscription games and microtransactions.
Sparkle pony (and flying derp lion) might well have generated, seemingly insane figures. $25m USD from what I've read, queues (lol) of people waiting for the transactions to clear. All very impressive. All very tempting.
What's not so impressive is the figures behind that. WoW makes about $2B (B as in Billion) a year. That's only 10% of WoW's total subscriber base handing over the cash for those items, if WoW was any other other MMO (and it could be argued that if Blizz had pulled a Richard Bachman then even WoW wouldn't be WoW) then 10% of it's subs buying something would generate nowhere near as much money, press or indeed subsequent PR material.
WoW's playerbase are also starting to squirm over the nickle and dimeing they see happening (cross-shard dungeons for MT, paid realm shifting, etc), Star Trek Online is a virtual wasteland, apparently, due to excessive microtransactions and yet that 10% figure generally holds true; only 10% of your customers will use the cash shop.
So if a small game like this one, still in its infancy, only has (for aguments sake) 3,000 subscribers... that's at most 300 people willing to buy the PO equivilent of Sparkle Pony. That figure also drops if you game allows/pushes multiple accounts... people are only going to buy one sparkle pony for their main after all.