Lots of cars have horizontal mounted oil filters. Are they also of poor design?
If you make a mess removing (oil leaking out over frame and other parts) an oil filter due to its location, then yes, it's a
poor design. Just because it's MB don't think everything they do is perfect. Does anyone remember their incredibly stupid bowing down to the "greenies" and putting self-destructing organic wiring insulation on their wiring harnesses? No other auto manufacturer did anything so incredibly poor in design or execution regarding wiring; pity the people that suffered with this nonsense.
In a commercial oil change place, they may, on a lift, be able to quickly remove the filter, and drop it in one of those elevated collection canisters. Perhaps a minimal mess, easily cleaned. Cleaning is much easier on a lift, rather than on your back, and even at a dealership, very difficult to do without leaking oil on parts in the way. But really, is it necessary? A vertically mounted filter allows an oil change with little to no mess...which is a better design.