No i meen, why so many addresses ? Are you only using one address or are you using many addresses on you Trezor/Nano ? ( erc20 )
Privacy. Here is a TLDR:
If you use the same address each time you receive funds, it becomes easy for anyone to track your entire payment history. This method of address generation improves privacy by automatically presenting you with a new address when youre expecting payment.
Does it not matter what address i use on the Trezor/Nano ?
It doesn't matter. You can use any address as many times as you want.
So i can just pick one address on my Trezor and only use that one ?
Yes.