In reality, the trebuchet fired twice an hour on average (unlike most depictions)
Got a cite for that? "A 1991 experiment conducted on a model made to ancient standards at the University of Toronto showed that a well-coordinated trebuchet crew could fire four rounds per minute." Although, later on the same article says the bigger, later versions were very slow... but hurled huge stones. There's a size / range / rate of fire tradeoff going on here.
For example, allowing a pikeman (typically good vs cavalry) to have a shield at all times, which is good vs archers, it just too good. Enabling a pikeman to temporarily lower his guard (lose his bonus vs cavalry and some defense) to move faster (get closer to archers) through the use of some sort of rush/charge command (stamina based let's assume) isn't powerful per se, but if you have a lot of pikeman, and the opponent has only archers at a safe distance, it allows you to take calculated losses to charge into them disallowing them any hope of escaping.
I don't understand this one. Fighting in a pike formation takes a lot of coordination and drill. I'm not reading anything about raising pikes to move faster on the battlefield, then lowering them again. Let alone shields, how are you going to carry a long pike and a large protective shield at once? Unless we're talking about "magical" pikemen that are unconstrained by physical reality, and exist only as game design conventions to describe a given pile of statistics and capabilities.
Imagine waiting for 10++ minute for the opponent to starve and turning into a stale game though this scenario is unlikely. In my opinion, I will prefer games where you fight away from both your own and enemy bases. Instead, I prefer fighting in the open where military strategy and micro prevails like a standard RTS game.
The Romans had this preference as well, and it's why Hannibal kept on defeating them. Fabius Maximus came up with a strategy that worked, namely denying an opponent the opportunity for decisive battle, but politically it sucked for him. So I think as we examine all these various "concerns of realism," talking about the valid challenges it can offer, we also have to consider the "concerns of attention," how long someone wants to be doing X in a game. From this standpoint, promoting "seige as good" can be seen as a priori flawed, as it only maximizes one set of concerns.