I don't see how you can say that with so much real life recent examples in the last ten years.
Examples of what, exactly?
I'd imagine any city has a garrison, city watch, police force, etc. (depending on the era) as well, if militias alone don't satisfy you.
And none of those are professional armies. Maybe they could provide a barrier to some underteched army, but not if there's enough of them to literally surround the cities, or if they are actually up to current standards.
(And the garrison is present in Civ V, except when it's been destroyed by the aforementioned army surrounding the city.)
And no, that's not how it's been working out. I say this from experience, with far more than a few units. Unless swordsmen are that much better than the pikemen and horsemen I've had access to?
Could you give specifics? You're complaining about having to move pikemen to make room for your slow catapults in one breath, and then claiming it's taking you dozens of turns to take a city in another.
You say that like they're contradictory.
Specifics? Well, it's been a while since I've played, but I remember surrounding cities with as many melee units as would fit adjacent to the city, adding as many archers around those as would fit, shuffling units to try and cycle the weak ones out but eventually deciding that it would be easier to just attack every turn and cycle new units in when they died. And it took a rather inconveniently long time to actually whittle the city's health down enough that I could take the city.
Also, I'm pretty darn sure I didn't have siege engines when that war happened. If siege engines are a requirement for wars to not be tedious, you should provide siege engines earlier.
The former sounds kind of trivial, like you're complaining about not being able to smoothly avalanche another empire away in one giant wave like you could in previous games. With the damage cities can do to attacking forces, I'm not even sure how the latter is possible unless you're cycling out (or maybe Branniganing and the replacing) just a handful of troops that aren't quite up to the task.
It's less "War is hard wah" and more "Okay, I've got enough troops to cover their countryside. The city is surrounded with waves of troops. This shouldn't take forever. Why is it taking forever?"
I suppose that's more or less what I was doing. Why, what else do you do if you can't get siege engines there, whether from lack of roads, distance, or not having researched them?