I agree with your post to a point, it's very intelligently written may I add.
However, the uniqueness of each nation in the game is now an essential part of the CIV, and the UU's, UB's and especially UA's of each are what differentiates nations from one another.
However, I'd like to try and play a version of Civ with the rules you have mentioned, sounds very intriguing.
On the other hand, would a game like that still be called Civilization?
Perhaps, but the historical element of the game, with historically accurate leaders, units, buildings and other elements would end up being meshed into a game no longer based on history as much as the previous iterations, a different genre, I guess.
Right now, the 'uniqueness' of each civilization in the game is artificial, and therefore not Historical at all. 'History' comes from a Greek word meaning 'to learn by study'. but the UUs, UAs, UBs etc are not Learned at all, they are given and based on the given Game situation, may be utterly useless.
As a single (Worst Case) example, I once restarted a game 15 times as Morocco without getting a start position that was both in a desert and with a Trade partner within trading distance. In other words, the UA, UB and UU for Morocco were of minor or no use to the player. What then, is the point of such Attributes?
Instead, make the Attributes applicable to the In-Game Situation, either At Start or as the game develops. This also means the Attributes of a civilization will not be based on a single aspect of a civilization. For example, England now is represented by a Medieval UU (longbowman), a Renaissance UU (Ship of the Line) and a Starting Naval UA (more speed for naval units). Which means, the English Rule of Law that came out of the Enlightenment, the massive English/British trading networks of the Renaissance and later, the ability to rule administratively a huge Empire in the Industrial era, and their spawning of numerous Explorer-types in that same period, all are missing. This also shortchanges every other civilization, in that the Ship of the Line was built by every European power that had a navy between 1690 and 1820, but is now artificially Forbidden to them.
Similar examples could be given for any civilization that has existed for any length of time - which is why almost every iteration of the Civilization games has had different Attributes, and frequently differing Leaders for them.
If you really want to play a straight (and strait-jacketed) civilization, then the Starting Position has to represent the actual historical situation: A Starting Option for Historical Start, in which England will always start on a heavily-timbered island just off the coast of a continent, Sweden will start on a mountainous semi-arctic peninsula of a continent, and Morocco will always start in a desert. Otherwise, you wind up, as I have all too frequently, with a Starting Position that makes no sense at all in relation to the 'Attributes' of that civilization: an Inland Byzantium, an Arctic Venice with no City States within 20 tiles, a Montezuma starting in the desert - these are all actual examples from my games, and they make a mockery of the current system of Attributes.
This does NOT mean that every civilization would start the game with a 'clean slate'. Civ has always, to my knowledge, used 4000 BCE as the 'Start Time', but a lot of things happened before that point in time. People living on the coast had learned how to make boats and exploit off-shore islands and resources. People with the right raw materials and requirements had learned to fire pottery, domesticate large and small animals, make religious monuments of very permanent aspect - lots of the current in-game 'Techs' in fact, could be available to a civilization from the Start - based on that civilization's starting position. This also extends to Social Policies and Religious Beliefs.
I would change the starting sequence of the game. First, select a civilization or possibly just a civilization-type, such as Desert, Nomadic, Forest, Island. Then, you go to the map. Based on your starting surroundings, you then get a Starting Tech, or Starting Tech Choice - which, for an Island civ, might be between Boating and Pottery rather than Agriculture, for a Nomadic civ might be Animal Domestication. There are mountains nearby - they will likely give you a different Starting Religious Belief than if you started in the jungle, or in a desert, or (extreme case) next to a Volcano.
In other words, even if you call yourselves 'Egyptians' in 4000 BCE, if you start on a well-timbered island it might be you who first develops the Ship of the Line in 1675 AD instead of those English fellows who started in the middle of the continent with horses nearby...
And yes, I want to be able to rename my civilization at any time in the game: why shouldn't I start as the Celts in 4000 BCE and become the Gauls in 500 BCE, the Merovingians in 800 AD and the French in 1200 AD? The game could even offer hints as you go:
"You have now built the Parthenon and developed Philosophy on your arid and hilly land: why not change your name from Faroffistan to Greeks?"
And, finally, your first city would give you a set of First City Names, ranging from the appropriate (London on an island coast, Thebes on a desert river, Baghdad between two desert rivers, etc) to Random to Your Choice. And, contrary to the current, limited model in Civ V, I want to be able to move my Capital as required (with appropriate penalties) and rename it as my civilization's Attributes become more specific to a single historical model (or not!) throughout the game.
I LIKE having civilizations that are different, that don't play the same way, that from the start are a unique - but I want the unique parts to make sense within the Game, and to have some relationship to the 'history' that I am 'writing' with my play of the game.