I am with OP on this. I have a hard time using my GUCs. I am OK with someone paying or mile-up, Delta has to make money... but of my frequent routes to Asia, I've seen time and time again non-rev employees goes in front of GUCs. I don't care what people tell me that's the other way around - my personal experience is always the opposite.
I call Diamond desk and usually there is no seat, so I am waitlisted. 2 hr until departure, there are like 14 open D1 seats on a 777. I call Diamond desk and ask why I haven't been cleared, they said seat is under airport control. I then speak to the GA and ask why I haven't been activated if there are 14 open and her reply - we have a lot of non-rev employees and their families on this flight... The story is very consistent, time after time.
Delta IT may think they are a very tight system, but near departure time, the GA has nearly full control over seats... One time the stupid C+ upgrade bumped me from row 44 aisle seat to mid of mid in C+, even I had that segment opt out. I spoke to the GA and the seat history show I was in row 44 and system pushed me to mid of mid C+, twice, but my original seat was occupied. She asked if I would be OK if she block an entire row for me, but it would the last row, near the restrooms. I said "no...I am surprised you would consider putting a Diamond in the last row". She goes "I figured..." then started to bump the passenger out of my original row 44 seat and put me in that seat. She then made a PA for that pax to pick up his new BP. With this much control, they can give out D1 seat to anyone... On time, I literally watch the GA boarded plane to a D1 seat and had a chat with the passenger and based on the conversation, the upgraded pax was a family friend.
Delta has good benefits on paper, but their IT is so screwed up on implementation, it's just crazy. We are at a point that no-status customer can buy a ticket and select a decent aisle or window seat of his/her liking and it stays that way, while us DM/PM have to constantly watch out for unwanted upgrade and then try to get original seat back. i am really tired of this.