I question the assertion that a metal enclosure is necessarily of higher quality than the plastic ones available. Many of them are cheaply made. That Vantec may work well, but it certainly isn't the most attractive case.
I disagree. Of course, the construction quality of products from different manufacturers can vary, but in general, metal cases will be stronger than those made from plastic, and it has the advantage of providing shielding, that both blocks outside interference and prevents stray radiation from the SATA - USB electronics in the case to the outside world.
The Vantec case is cast, not sheet metal, and the parts fit together well and securely. I don't think this is an unattractive case.
But for a 2.5" portable drive that requires no power adapter... After having used drives with attached USB cables, I'll never use anything else.
The weakest point in the construction of such products is often an attached cable. Typically, the insulation can crack at the entry point to the chasis which puts strain on the shielding and, eventually, to failure. If the cable fails for that reason, or any other, replacing it would require stripping the insulation from one end of an existing USB cable and all the individual wires, unsoldering the old connections from the circuit board in the chassis and soldering in the replacement cable... assuming you know how to solder well.
OTOH, if a non-attached cable fails or is lost, replacement USB cables are inexpensive and easy to find.
Another more subtle feature of the Vantec case is that, when plugged into a computer, it allows the machine to read the make and model number of the drive in the case, whereas some manufacturers' electronics mask that information and show only the name of the manufacturer of the case.