The thing is, all the mounts will do is entice people to level a tank until they get it. Added rewards would only entice people to level a tank for roulette (as well as instant pop), then never touch it again.

They are going about encouraging tanks in the completely wrong way. They need to look at why people don't want to play tanks and address THOSE problems if they want people to actually play tanks. It's the hardest role and the one that gets shit on the most if things don't go right, you need to be spot on and pretty much perfect in fights or things go wrong while dealing with an obscenely long GCD with no burst threat to speak of. It's not exactly surprisingly most people don't want to play a tank. Half the time I'd rather just sit back and mindlessly stab things and let others take the blame when something goes wrong.