I was going to create a thread about barbarians, but since you beat me to it, I'll add my thoughts on Barbarians here - with that said, I understand your complaint. There is a huge difference between Vanilla & Raging. I could totally get behind a middle ground. Personally though, I love playing with Raging because it forces me to build up a sizable army, rather than simply sitting back and developing my empire/cities.
As for what I'd like to see with Barbarians overall, I'd really like to see a return to Civ3's Barbarians and what that allowed. For example, unique units were allowed for Barbarians. I had customized a version of the Rhye's of Civilization mod back then, which included unique units for Barbarians and it worked extremely well.
I had added a unique unit for Barbarians & named it a Raider. It treated all terrain as roads (or it could move 3 tiles per turn if it had a move of 1, I gave it 2 moves,) it could pillage well, and it also had a retreat bonus so it could survive attacks better, but the point overall was that with a move of 2 (6 tiles per turn,) it could move into any Civ's territory & pillage or attack a Civ & then retreat. This slowed exploration (just in case nobody here knows, back then, Scouts had zero defense, so any hit would kill them, just like any hit now will capture Civilian units) and also forced a player to go seek out and destroy these units, as well as seek out and destroy the camps which spawned them. There was no need to put a huge pile of gold in the camps, it was already necessary to destroy them. Unfortunately, back then you couldn't customize the AI at all, so the AI didn't use the unit as well as it should have.
Civ3 also allowed an "advanced" Barbarian unit, or basically a second unique land unit for barbarians. For this, I created a unit called a Marauder. It was slow (only had a move of 1,) but it was strong. It would take multiple units to destroy just one of the things. However, again, the limitations of Civ3 caught up with me here, because there was a mechanic back then, known as barbarian hordes, which forced camps to spawn 8 of these advanced units, so I couldn't make the units as strong as I really wanted to. I wanted a Marauder showing up near you to be a reason to recall your entire army to defeat these things.
If we had these two things working properly, which Civ3 didn't allow, I don't thing Barbarians would need any other land units, especially if we took away any bonuses against barbarians. That was another thing Civ3 lacked, so everybody had to deal with barbarians equally.
As for sea units, Civ3 only allowed one, so I created a unique unit called a Sea Raider, which mimicked the land version, except it could do both ranged attacks and melee attacks. Unfortunately, Civ3 didn't allow an "advanced" sea unit for barbarians, otherwise I'd have added a Sea Marauder, which would mimick the land version.