We definitely need a separate arcade server and a "realistic" server, as those two play styles don't go together. Sadly, all servers seem to be fairly empty most of the time these days, and this would make that even worse.
Realistic server could then feature simulation of various issues on the line. I agree with @Gazz292's last sentence - perfect operations are kinda boring and it's one of very few things that I dislike about SimRail - unless someone screws up big time, the game gets kinda repetitive (especially since there's a clock-face schedule in the game, even though Poland is one of very few places in Europe which in real life still mostly didn't switch to it). Having random track closures, accidents and similar stuff to deal with would make the game more challenging and interesting.
Also, if you're being held for seemingly no reason, sometimes just asking helps 🙂 I had a case when a train stopped before the entry signal, I couldn't get in touch with him and it took me 5 minutes to notice that the signal stayed red despite the route being set. I quickly fixed it by giving him a substitute signal, but if he called/chatted me, it would happen much faster.
Personally I also try to give human-operated trains priority over bots, but within some reasonable limits in regards to what happens down the line - see noirceur's excellent post about timetable-keeping. Those technical stops and order of the trains are there for a reason. As a driver, I hate nothing more than being stuck behind a slow train on the main line for 20 minutes, because someone didn't give a damn about the timetable and figured "why not send a freight train that was supposed to stop here for 10 minutes in front of a Pendolino".