Most content creators and “serious” simmers fly without ATC whatsoever from what I’ve seen in the past years. Whether it’s because of the problems of the ATC system or because the constant radio chatter would interfere with their constant chatter, I don’t know, but most people who I watch / follow either use Vatsim or don’t use any ATC, just fly around.
Now, I use ATC all the time (default – I’m on Xbox) and for the purpose of what I’m doing it’s perfectly usable. They get me to the desired altitudes, get me down in time for approach and it generally makes flights much more atmospheric than flying in complete silence. My copilot responds to all radio messages so it’s really just in the background for me, making flights more atmospheric, and crucial for altitude. I agree there are issues with the system (sound cutting off, using the same voices as the AI planes, constantly requiring different altitudes over mountainous approach paths), but other than that I find it perfectly usable on a daily basis.
However, I can understand the system can’t really handle special situations, live traffic, situation changes, etc. It works only until you fly in a general fashion without any special circumstances. So I agree that it could use a full upgrade, but then again, I do think it’s generally usable and as far as I can tell more advanced simmers wouldn’t use it anyway. Even in case of an upgrade, I just wouldn’t expect human-level flexibility and intelligence from an automated system in a commercial game.