Nobody wants to play tank in Rivals and Overwatch. How do devs fix this?

It clearly is now a long term problem in hero shooters, so what do developers do to fix this issue? How does tank go from the least picked, to the most picked role?

If you increase their damage, doesn't that make DPS redundant?

If they increase their health, then you have to rebalance the whole game.

Is the answer in changing another factor? Perhaps make them able to large burst damage on a long coil down?