The point of them is more the overall story and grinding for rewards like the mount/minion, really.

They don't take long because things in MMORPGs used to consume your whole life to the point of not eating/sleeping. By providing things in bite-sized chunks you can more easily take breaks and look after yourself.

Looking at 1 daily in particular and saying it doesn't take long in isolation is missing the point when there are, overall, lots of other things that are also bite-sized that can accumulate in this way, but make it easy to take breaks between them.