There could be 500 tank jobs and it wouldn't make any difference. People don't tank because it's stressful and people have no tolerance for someone learning a fight for the first time when it inconveniences their pursuit of some slightly higher numbers. Personally I really enjoy tanking but I don't do it in PUG's for the most part because either they won't take someone that doesn't know a fight or you get abuse if you happen to not act flawlessly. The only way to get more tanks is to either make the role pointless or for the community to adopt a better attitude.