No.... leave the drive letters for pooled drives ...,... as is. It's useful for when you want to remove a drive from the pool. Apart from that ... no real purpose or reason to do so
The only time I have found it useful is when the drive to be removed had CRC errors and so Drive Pool couldn't copy the data to another drive in the pool before removing. In this case having the letter was required so you can see the hidden folder Drive Pool stores the files in and move the files manually.
If someone is happy with the process of removing the drive letter, I see no reason why not. In the end if there is an issue they can just add it back again and it makes the whole thing so much tidier. If you add unformatted drives to the pool, DP just quick formats them and adds them without a drive letter assigned anyway. It can be added back via Computer Management -> Disk Management if someone prefers to have the letters.
Of course, you could just mount the drives on a set of folders on your D: drive (assuming you still have the D: from the original install) and then you can access the files in the hidden folders if you wish and the letters would not be visible in Windows file explorer.
RB