That last part is what is important to me: if you can't see in easily, that means every time you want to check on your snake you have to disturb them, which isn't ideal for them, IMO.
And while bad situations are usually (& hopefully) rare, they can become much worse when not seen & caught in time, so for me, it's a safety thing too. Besides, that's a big part of why I have snakes- to watch them.