HA GET IT? EXECUTE-D?!

Ok sorry. Using the executes on adds and giving you a bonus from that isn't necessarily "bad" design, but it doesn't mesh very well with the rest of the game's mechanics. That's part of why they removed Mercy Stroke and why Sole Survivor is more successful. I agree with the above statement about the "FINISH HIM" because that's part of the subtlety of the "end of the fight rush"; having to deal with one more off-GCD.