Here's a fool-proof solution, since tanks are like dungeon GMs anyway: a free half hour of game time for each hour spent tanking in PUGs.-Keith
I say take it a step further and invert that ratio. Tank for an hour and get two hours free (excluding the time in the instance). Depending on how much they want to play (or tank), this could make it free to play a tank. Or free to play WoW in general with a bit of tanking.
Cue unintended consequences.
This would reward tanks slowing down. Marking targets, explaining fights, doing ready checks, and going afk for as long as they can get away with it. This could be prevented by making the time reward based on a standard expected instance time, let's say one hour (I have no clue). But that will just reverse it, making the tank want to hurry through and reluctant to accept slow groups. After all, if they can get one hour of credit in less than an hour, great, but more than an hour, not so much.
It still doesn't get past the problem of bribing tanks and expecting positive results. This isn't likely to bring in tanks who are merely hiding, since the time gained won't be all that spectacular, shifting back the sub renewal by a bit over a day per month (assuming one run a day), saving about half a month in a year. Would you tank for what is essentially $8 a year, without holidays or dental? For players who have left, this may bring them back in, unless tanking is why they left, in which case, why wouldn't they just pay the $15 a month and never have to tank?
I liked this idea at first. Tank a run then play for free. Maybe save up for a raid night. Except then the accounting brain kicks in. Even setting aside the dismal money savings, can you imagine if you started calculating the time cost of a raid by the number of randoms you'd need to tank? That much-desired 10 minute break now adds up to 5 minutes of noobs. That raid night of a few hours? Two hours of noobs. This causes an exponential increase in noob-induced stress, as guild members being noobs (causing you to spend more time wiping than you should), then causes you to spend more time with non-guild noobs.
Rather than actually concluding with anything, I'll instead hand you over to Adam.
5 man instance runs used to be, (a long time ago I might add), one of the most enjoyable things to do in the game. The second reason this is astonishing is the simple fact that Blizzard has designed the Cataclysm expansion around Heroic 5 mans. So we have a problem here. Blizzard has even admitted in the patch notes that doing these things might not be very fun. It’s all a giant head-fuck really because, I thought so anyway …
… that a game is supposed to be fun.