It would be interesting to compare what the action budgets for each tank were across each expansion, but I haven't seen a good archive of the old action lists. A lot of Shadowbringers' PLD's 'design' comes from the fact that it just has a bigger action budget than the other tanks.

More actions doesn't necessarily translate into more engaging (most MOBAs use surprisingly few, as an example), but I think a lot of the fan favorites just had more buttons available to press.