Just wanna defend the speed boost on Expedient a little. There are some mechanic sets that require a lot of movement that people were already using Sprint on regularly, maybe not out of necessity, but to make it easier or get a little more uptime. Just a few recent fights with movement heavy sections include: Eden's Promise (Savage), Emerald weapon (both normal and Savage), half the bosses in Nier raids, almost every fight in Dalriada. And that's just looking at the last couple patches.

Now you can say, "Just use Sprint then." But Sprint isn't always up for every mechanic that you might want it on. Expedient is also twice the duration of Sprint (in-combat). And this is really tiny, but Expedient also saves everyone an oGCD slot that would be used on Sprint.

So yeah, sometimes you'll use Expedient like a 20s Shield Samba just for the damage reduction, and sometimes you'll use it just for comfort in movement-heavy mechanics. And occasionally it will feel like a godsend when you need both effects (particularly in Savage and Ultimate).

Very rarely, I think, will you wish you had a Sage instead for Pneuma (their level 90 counterpart to Expedient), which just gives a 400 potency heal instead of the speed boost. The game is flooded with 400 potency heals. But a team-wide speed boost is uniquely useful.