I'm not sure about fluidity but alot of people enjoyed actively switching tank stances in battle and it was not all about DPS. Stance dancing was a form of "Pushing it to the limit" for them to see just how far they could take it. Now that SE is actively punishing the stance dancing, people don't know if they should anymore. Losing half the beast gauge over and over again is a pretty hefty loss.

Part of the DPS changes brought a smaller gap between pld and the other 2 tanks. Since all tanks are doing a little bit less damage, the gap has closed somewhat cause its relative. The smaller the gap between pld vs DRK and WAR, the more pld will get choosed cause it brings more than just DPS to the table. PLD has a much stronger survivability currently than WAR in my experience as well.