Well, I really don't think it'd take that long to complete. But let's assume it takes 77.5 hours to complete. And let's break it down into 2 hours a day (approximately 39 days). That's slightly over a month. 39 days, decent play, for a superior weapon that's guaranteed as long as you do the work sounds pretty reasonable to me.
How many of us went months or years before we finally got armor we were after? Salvage? Dynamis? And no matter how much time you spent in Salvage or Dynamis (or a HNMLS), you were never guaranteed a final product in the end.
With Magians, you are.
I don't think the exact trials are enjoyable, and like I said before, I think there should be a maximum of 200 monsters required for any one trial. The enjoyment, for me, is the hard work and the guaranteed reward for said hard work.
As far as I'm aware, I think most jobs only need about 1~2 Magian Weapons? So even if you have multiple jobs, it shouldn't be much of an issue.
The jobs I can think of that need large amounts of magian weapons are BLM, RDM, SCH, and SMN.
Why shouldn't the magians be superior? If people put in the time and energy into making something, I think it deserves more power than an item that doesn't.