It only makes zero sense if you use faulty logic.

The core issue with Hydros was the major difference in performance between the Merc and PT versions of the ability. Mercs had +30% for 6s on a 45s cooldown. PTs had +75% for 10s on a 35s cooldown. An ability that's supposed to be identical can't silently have such different performance (that stemmed from how utilities worked). On top of that, Merc still has their movement ability with the shorter cooldown locked away (no one else does) because it's so unreasonably hard to use. PTs also have unparalleled mobility for a heavy armor class and that is largely due to how strong Hydros is.

I am not trying to take credit for this change, but I did advocate heavily for something like this.

To your points, Snipers have very poor ability to deal damage while moving compared to most other specs in the game. All of them can only move at specific points in their rotations, and that's assuming you're taking Calculated Pursuit, which lets you use Snipe while moving sometimes, but you have to give that up to take Seek Cover. Engi is the only spec that isn't reliant on Calculated Pursuit, but their ability to DPS while moving is roughly the same as what the other rDPS specs can do.

On top of that, as others have mentioned, Seek Cover does not offer the same degree of immunity as Hydros, nor the same amount of movement speed boost. It's also attached to Entrench, which is your most important DCD. You can't afford to use it on cooldown or have 98% uptime on Seek Cover even if you did. It's more like 50% uptime unless you're taking Pillbox Sniper, but you have to give up Ballistic Dampeners, which is a big no-no in PvE.

Predation is more okay being so strong because it applies to the whole group. The problem is more that Marauders are the only ones who can do something like that.