Well, I don’t make full use of the skills because I want a richer tactical experience. Also, you can’t always use direct fire, even with skills. For example, Tritons are quite adept at making good use of cover — you often don’t have a clear shot at them, and don’t want to send snipers into stealth mode by failing to disable the torso. In such cases, OW is a better option. With Myrmidons, it’s often the only option, so it’s crucial to use it well.
Reading the posts here, I get the strong sense that I play the game differently than many. I don’t clear missions super quickly, and I make extensive use of tactical fire and movement. From my perspective, PP gives an excellent tactical experience. Most of my issues with the game are with the strategic layer.