God, just stop with the excuses people. An archery unit is not going to survive combat with a regimented rifle unit. That's ludicrous and you're making yourselves sound like apologists.
You're making yourself sound ignorant. Early firearms had less range and a lower fire rate than archery units. It wasn't until rifled barrels gave the guns range and cannons some devastating field oomph that gunpowder-based armies were markedly better. Of course, archery training took years and years, while just about anyone could be drilled on basic musket use and then sent to the field to fire in volleys.
Crossbows had enough power to penetrate anything but the heaviest armor, too. Look up the physics on how they were launched - the forces involved when a bolt was fired/struck were incredible.
Now, as guns became more modern, able to hold larger chambers, more accurate, increased range, automatic capacity, etc their abilities went so far beyond that of archery that it got ridiculous, but 1700's gunpowder? Keep dreaming.
I've murdered the AI's archery units using knights, so there's no reason they're smacking you silly when you're fielding later stuff anyway. When you have the advanced units, you *do* have an advantage, and if you play better tactically you'll win handily.
Or just tech infantry and laugh at their damage.
Other issues are a question of gameplay > realism, which is the RIGHT decision, by the way. If the game was set up such that 1 modern unit could just mow down everything, it would be imbalanced to the point of everyone either rushing that unit or trying to time out a KO on the other civ before they can field it...a lot less dynamic than what we have currently. Troop spam does NOT win in this game like it did in the others, and that's a big step forward.
Civ V has tons and tons of flaws such that it plays more like a beta than a finished product, but OP complaint isn't one of them.