The Gladiator II example is just lampshading. If you just wrote "the prisoner grabbed the weapon the guard brought in to the cell, and then killed the guard with it" the very first thing someone's going to ask is "well why did the guard bring a weapon in?" and then the writer says "oh well he didn't consider it a usable weapon" and then "but clearly it is, so that doesn't really solve anything" and rather than coming up with a better escape method the writer just leans into the absurdity of it - the on the nose dispensing of folksy wisdom establishes that the guard is just an idiot rather than leaving the audience to contemplate the contrived situation.
For Megalopolis, “What do you think of this boner I got?” [he shoots her] isn't exactly a compelling scene when reading it. It makes a lot of sense to punctuate the scene with some emotion to make it make some sort of sense. Can this emotion be shown on film without dialogue? Possibly, but the writer can't be sure how it'll actually look, and they need to convey to both the actor and director what emotion needs to be conveyed. It sounds like placeholder dialogue which could be cut or changed as needed.
For the Apprentice, again the writer likely doesn't know exactly how the scene is going to turn out. Is "Trump Tower" going to be clearly legible on the model as the scene is shot? Do you even want to spoil it by showing the name on the model? The point is this is supposed to be a reveal.
In all three cases, these lines very well could be great with proper setup and delivery, or perhaps could have been reworked into great lines. The issue is just these are mediocre films. None made any serious attempt to polish their scripts. It's not a deliberate tactic to dumb down movies or deal with poor attention spans, it's just the makers of the movie saying "eh, good enough."