The community has agreed over time that this is the way they want to clear the content.

It's not really the tanks choice. If he was going any slower a DD or healer would just run ahead and pull everything.

To deal with it you have to stay close to the tank at any time. Only use sprint when the tank uses sprint or you will have trouble with keeping up with him when your sprint is on cooldown and the tank runs ahead.

Start casting heals before the HP of the tank actually drop. As soon as the tank stops moving start to cast the heal.

When you pull aggro move close to the tank so he can grab the enemies from you.