There are a lot of ways for a rogue to get sneak attack in 5e.
Hide is contentious. If you allow duck-behind-cover, hide, shoot around corner, you basically get the steady aim back when you get cunning action (with a check).
But the Hide rules are intentionally vague, so a rogue who wants to snipe at all like that has to rely on DM fiat for it to work.
This looks like an attempt to permit a rogue to reliably get sneak attack, even without an ally in melee range. It has a cost (bonus action and movement) which isn't trivial; but for a rogue in a sniper nest, it ain't bad.
For a melee PC, it is usually worse than an offhand attack (2 rolls for 1 attack < 1 roll for each of 2 attacks).
I could see a Paladin who was already going Assassin 3 (for alpha strike pain) making use of this. They can be sword+board and get an improved chance to land a crit so long as they stay put, without burning their offhand for another swing and losing that AC.