On the one hand, many players really like 'unique' Civs with unique attributes that make them very different to play from other Civs in the game.
On the other hand, a Civ that cannot make any decent use of certain types of maps or map configurations (classic example: a navy-oriented Norway or Britain in the middle of a Pangaea map) or deal adequately (read: have a bonus for the gamer) with combinations of AI Civs and IPs will cause rage-quits and vociferous complaints from gamers.
There is (so far) no middle ground that satisfies everybody, so Civ VII has largely gone with Civs that, by gamer configuration using Leaders, Momentos and other modifiers can be almost anything to anyone, for anyone in almost any game.
Personally, I think the problem is not in allowing 're-configuration' of a Civ for a particular game, but the fact that Civ VII's system makes you pick your Leader, Civ, Momentos and other 'specialization' effects before you see the map and your neighbors. Therefore, any attempt to specialize your Civ is partly random and may not be appropriate for the starting situation.
The simple "(map) starting bias" which is all the game has now is woefully inadequate and can even be misleading: a 'rough coastal' bias can put you on anything from an inland sea surrounded by mountains and jungles to a seacoast of rough Tundra (and yes, that has happened to me more than once).