As posted above, it is daring (bold) to call upon God as Father, and was especially so in the day Jesus taught this prayer, as the people of that time didn’t view God in that familial sense.
Also, I think this is a translation issue as well, using dare where we might actually mean “proud” or “honored” or “humbled”.
Also, bear in mind that in the time of Jesus, people prayed via the priest more often than directly to God (or at least, that’s my understanding). In a similar way, at Mass, the Our Father is one of the few times we (the assembly) address God directly rather than via our priest or in indirect language.