(car salesman mode)
Well, I'm glad you asked
(car salesman shot)
More seriously, here's one case, and one reason I really like it:
Your send your fleet through a wormhole to kill all the guard posts on a planet to cut down its reinforcement rate; previously you could:
1) shift-click a move path over each guard post
2) alt-shift-click an attack-move path over each guard post
3) shift-click each guard post (and optionally all the guarding units around it to make sure they're not there, if you're planning on building resource collectors)
4) put them in FRD and forget
But there were some problems:
1) they wouldn't stop, even if they didn't kill the guard post during the pass; also, many of your ships would wind up getting closer than necessary since they need to actually move to the move point
2) they would stop, so you know the guard post will die (if your fleet doesn't), but they'd also stop to engage stuff along the way and you may be on a schedule; also they'll still move to the actual waypoints, thus spending time and perhaps exposing themselves to unnecessary fire
3) this is difficult to do without zooming in and out a ton, particularly if you want to, for example, kill all the turrets there too
4) offensive FRD doesn't work so well
But now you can:
5) queue up a paint attack order with a rectangle around each guard post's cluster
So they will
- make sure the targets die
- only move close enough to have a good hit rate, not close unnecessarily, and not actually move to the waypoint, which can save a lot of time particularly with long range (and slow) ships, like missile frigates, zenith bombards, and snipers (who generally won't move at all in this case; if you're one of those folks who wipes guard posts with a full cap of each sniper mark this can be a big difference)
- not require a lot of clicks or a lot of zooming to issue the orders