gaming screens typically have terrible viewing angles and poor picture quality, optimizing for low input latency and high refresh rate. While I probably wouldn't buy a very expensive monitor at this point that didn't have a high refresh rate, I'd certainly pay for picture quality, viewing angles, resolution, and maybe just appearance before refresh rate. As an external display, you'd need gpu power to drive the display anyway, and I'd take my 30" Dell 2560x1600 IPS over some PoS 1080p 120hz TN panel.