Why is formality any more natural for a user interface than casualness? This seems like an extremely arbitrary personal preference masquerading as reasonable criticism, no different from getting riled up about the fact that Windows default theme is blue when it should _obviously_ be green.
> Computers are our servants, not our friends. They should act like it.
I had a live-in housekeeper for a chunk of my life, which is roughly as close to "servant" as one gets in the modern West; we communicated in normal, casual English. If you are going around insisting that service workers address you like an aristocrat, you're an enormous asshole.