Why Do People Use "Precision" Bidding in Bridge?
I think Precision is - with some caveats - an absolutely brilliant system, and one that everyone should try out at some point.

I used to play Bridge with, not to put too fine a point on it, a group with players of various different levels of skill.  Playing with standard systems, some of them would just not get it quite a lot of the time.  Presented with anything other than a balanced 1NT hand, they just wouldn't really know how to bid it, much less respond, or deal with an overcall!

The beauty of Precision is that it takes a lot of the mystery out of at least the early game.  A junior player can't fail to alert you to their strong hand if they are in first seat with 20 HCP.  Likewise, they tend to have less trouble finding the correct suit and level, because of Precision's tightly circumscribed bids.

Is Precision better than other systems in the long run?  No, because once you have a genuine feel for the game you don't really need a system with so little room to maneuver.  Your talent and ability to think quickly will fill in any games in a looser, more economical system.  But don't underestimate Precision's value to beginners.

As for your problems with the 1C opening bid to indicate a strong hand, you might as well say you have problems with conventional bids in general.  Conventional bids are shortcuts to success, taking the place of bids that would otherwise have little value.  1C is a terrible bid, in a literal sense - I have not especially good points, no good majors, and strength in clubs?  Well, that's not going to get me very far, really, is it?  Unless I have 80 below the line or something.  It's almost never useful in actual practice though.  So being able to indicate a strong hand while retaining a whole level of bidding space is usually much better.  It gives you an extra bid and response to accurately describe your hand to partner, and reach that slam that a 16+HCP hand is often capable of making!