I do see a problem with people charging to distribute an addon. Not only will it give those with more IRL money an in-game advantage over those without it (however minor), it's also making money off of blizzard without cutting blizzard in. By that I mean, if WoW didn't exist, these addon creators wouldn't be getting that income. I sympathize that creating and updating an addon takes time that could be spent doing something else, but no one's twisting their arm to force them to do this. Very often, when an addon creator stops updating an addon, someone else steps up and takes over for them without expecting any kind of compensation.
Glider wasn't an addon, it was completely automated gameplay, i.e. cheating. The only way they got away with charging for it in the first place was because those brazen arrogant douchebags were doing it in direct defiance of the EULA and multiple cease and desist warnings. I've never seen a legitimate addon you had to pay for, and I've used most of the major addons available in this game.
And blizzard obviously doesn't care if kind people donate to keep the addon up and running, so long as the solicitation doesn't occur in-game.
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(USER WAS AWESOME FOR THIS POST)AFK: Attack, Fight, Kill! The healer is telling you to go pull mobs.
WTF: Way To Fight! The healer is applauding your tactical genius.
OOM: Out Of Mobs, go pull more.
"Being around you makes me feel nicer [by comparison]."
-Valaheea
"You can't use math to determine (your) spec." - Vomit of Ursin, on rogue class mechanics