McGrath50 that's another issue with cadet pilots with no experience being in a place where they shouldn't be in the first place! Seniority only works to a point, a DE with more hours should get further sooner (I'd hope!) but I know I'd be annoyed if a cadet was bumped up ahead of me after working so hard to get into a jet and not having thousands of dollars to buy my way in.
There will be a breeding of pilots who will not have any command time with cadet programs. What happens when all the captains retire? It's a big issue for the future to consider. Sure 'filling the right hand seat' works in the short term.
Consider also, a 200 hour pilot is in the RHS of a jet. The captain becomes incapacitated. All of a sudden a pilot with no command time is in command of a multi million dollar aircraft with hundreds of lives on board.
As for some people coming out with 'GA creates bad habits'. If you allow it yes they can creep in. However, airline SOPs are concrete and a checky will belt any bad habits out of you.