What is the "bezel" and why does Dell charge 15€ for it?

Solution 1:

The bezel is attached to the front side of the server and it protects the hard drives and the power button from removal or accidental usage. The bezel comes with a key and a lock but it's not necessary if the server itself is only accessible by you or your administrator staff.

In my opinion it is just an aesthetic choice. We're using about 120 DELL servers and we don't have any bezel installed.

Solution 2:

It's a bit of plastic that makes the server look less like the metal box of bits it actually is and more like the sort of thing that management-types have been led by salespeople to think servers look like - i.e. it's purely aesthetic - nice of Dell to give you the option I guess, not many other places do.