The difference in detail between the two isn't that great, and if you're sitting far enough from the TV that the square minimap is too small to be helpful, then the same holds true for the round minimap.
The only way I can see this being true, is if you're using a small TV, or sitting so far from the screen it may as well be a small TV. The second, is the square minimap is too small to be of any help.
I'm used to certain things being certain ways myself, and changing it feels weird. So far I've heard three reasons for using the round minimap instead of the square minimap. I'm seriously beginning to question some of the veteran tankers ability to read a map.