It'll not influence the top league, and the lower leagues are rather competitive anyway: it still doesn't generate interest, nor attract youngsters to go out on loan.
Having a Rangers 'B' team in League Two will generate more gate receipts for the lower league clubs, generate a bit more interest etc.
It is inherently selfish: a 'B' team bridges the gap between youth-team and first-team for the side (Rangers, say), but the youngster remains in the Rangers mentality, play the way the first-team play, while getting 'first-team' experience.
It produces better players, and even if they don't make it in the first-team, they'll filter down into smaller clubs.