It's funny, because to me the opposite is true. Less transparency takes me out of the game, forcing me (as both a DM and a player) into a sort of meta-game of guessing if there's really a DC, if the DM is just making it up, if my actions actually matter, if using that power that boosts my rolls is going to be a waste...
I guess my experience comes from playing with a DM who, on the surface, really let us do whatever we wanted as characters, but the only actions that really mattered were the ones that followed her preordained plot. So we could invest in an inn, adopt an orphan, research hidden treasures... But none of that really mattered unless because once we were done the DM would just say, "Okay, the next day you receive a message that..." and the plot would move forward, our actions having made no impact.
The same thing would happen with skill checks. It really didn't matter what we rolled when trying to convince the king to grant us extra magical weapons so we could go kill a demon... If that was part of the plot, the king would say Yes no matter the roll, and if it wasn't the king would says No.
For myself as a player, I really like to be told the number I need and the consequences. It makes rolling a lot more exciting and impactful. If the DM says, "This king is very protective of their treasure... You need a 25 to convince him, though a 20 will get you a discount at the royal magic weapon market. Oh, and if you roll below 10 the king will be very insulted."
To me that creates a lot of excitement as I get ready to roll my d20! And I'm able to easily translate all those numbers to in-game things my character is noticing.
I know that doesn't work for everyone, but hopefully you can see why it works for me, and why I don't consider it bad DMing.