First of all, I don't hate anyone for anything like this, I just don't understand them sometimes.

I can see the creative installation thing, I just like for the overall finished product (the car) to make sense as if it were being produced and sold, even if it is fashioned to individual tastes. I tend to favor simplicity and functionality (high horsepower I would put under functionality, but I'm not usually a fan of trailered cars).
I guess I like 3 things about car modding: creativity, learning, and a nice finished product (even if it is ever-evolving). I guess I see an excess of TV monitors as fitting only the first 2 of those. Some may disagree, and that's fine. If everyone thought alike or followed the same standards, then overall progress of technology and creativity would be hindered in the end. Sometimes the most excessive things produce the most useful things, with refinement.