No, having a 144hz monitor is great whether you're always hitting 144fps or not. Think of it this way, the graphics card supplies a frame and the monitor "grabs" the frame and displays it to you. If you're running a 144hz monitor and only getting 72fps, then half the time the monitor asks for a new frame, the GPU won't have one. However, you're still seeing 72 new images per second, as opposed to 60 on a 60Hz panel. If you play games like CSGO, then 144hz is an absolute must, otherwise it's just nice to have. For what it's worth, I'd turn down a couple settings (AA, Ambient Occlusion, shadows maybe) so that you can have 100fps+ as often as possible, but it's up to you.