Colloquial writing style in UI messages

Nowaday I often see a colloquial or even flippant writing style in UI messages. For instance MS Excel 2016 writes "We finished $task", "Spelling finished. Let's go ahead!" (Translated from German "Jetzt kann's weitergehen"), Youtube on iOS announces an update with "garbage brought away, ..., time for a nap.", GIMP "Eeek! $Error" etc. The messages might be meant friendly, but at least the Youtube message is literally telling nothing and I am a bit wondering. They remind me of Microsoft Clippy. Are these messages the results of serious user research or just a marketing attempt to appear modern and friendly?