Even at ~100 dpi, the grainy character of matte coatings from that era was noticeable; my 2006 iMac and a Dell Ultrasharp from a few years later were both unmistakably grainy in a way that glossy displays are not. At the time, the matte coatings were an acceptable tradeoff and the best overall choice for many users and usage scenarios. But I can imagine they would have been quite problematic when we jumped to 200+ dpi.