I don't understand your point here. Like, true, these rules weren't things at one point. But they are now. So what are you getting at? Split fire is a thing, vehicle movement is typically higher than infantry, terminators can run, Power fists and stuff doesn't do that anymore.
As for the Random Mission thing, yeah kinda. What changes between missions is where the objectives are placed, and your deployment zone. But Primary objectives is always scored the same way, so the variance comes from Secondaries, and thebestmost reliable way to win is to pick the Secondaries that aren't dependent on your opponent at all.