Charging port under the mouse is a non issue too, the battery lasts for weeks and even if you need to charge it in a pinch, you can plug it in for less than a minute and you’ll be good for a few hours.
It is however extremely good at making people talk about it, and that’s why they’ve been keeping it this way for 10 years
Because it has obvious room for it. The shape of the Magic Mouse doesn’t have any, and a hole at the front or back would look stupid.