Defend orders on other players is just an easy way to get free extra WP, and you don't actually have to defend the player; in practice I've never seen anyone defending the player who has the defend order on them. If the ability to place defend orders on players was removed, then people will actually place orders on things like objectives and CRUs, and actually defend things. The dominant strategy is always to set the defend order on a squadmate, because it generates free WP, which then makes getting precision strikes easier.

The more favorable alternative is to make defend orders not give extra points to the player, but instead give bonus WP for actions to squadmates near the defend target; would incentivize the squad to actually defend the defend target, instead of getting free WP from the target's actions. This should not only apply to players as defend targets, but also for objectives and installations.

Maybe we could even see someone using a capture or attack order for once.