That depends on your definition of fun.
Personally, I think you should be getting shot at by hidden enemies if you’re invading an alien cave system, and my fondest memories of the XCOM games comes from those missions where you were cautiously advancing with a sense that anything could come at you at any moment - the Great Nantucket Whale Disaster was a perfect example of one such: I was so wound up by the time I got to the ship, it was a relief to discover it was just an infinitely spawning Chryssalid nest.
And you can automatically generate light to the radius of your Perception range. So you don’t have to spend APs on it at all.
Also, whether you dismiss them as ‘detection mechanics’ or see them as a perception issue, limiting the distance you can see on maps would go some way towards limiting the vast movement and firing distances that you (quit rightly) see as main problem with this game.
Forget darkness for a moment. For the game to have suspense, there has to be some kind of Fog of War, with a sense of unknown dangers lurking round the corner. Atmo, there is none. With the occasional exception of a hidden Chiron at the back of the map, you pretty much know everything that’s on the map by Turn 2, and then all you’re doing is planning how to take it out in the minimum number of moves with the fewest casualties possible. An interesting mental exercise, but hardly an experience of creeping Lovecraftian horror…