It's a CBA item NOW (as the rookie contracts are basically locked to their draft position)... but I don't believe it was initially cut to 7 rounds directly due to the Union.

Obviously the NFL fights ANYTHING that the Union tries to do, and the Union usually returns the favor... especially since it would take away from players freedom.

That being said, I do they they should have 10 rounds or so. 7 doesn't seem like enough. Of course, technically it's 8 rounds, as they get out 32 Comp picks each year. But how about this, a total of 320 picks each year (10 rounds) if that's via normal draft order or extra Comp picks.



From the Internet

The NFL reduced the draft to seven rounds in 1994 to align with the modern era of free agency and salary caps introduced in 1993, reducing the need for teams to stockpile prospects through long drafts.

This change reduced costs, allowed more undrafted players to choose their team, and provided better scouting utility, down from as many as 30+ rounds in the 1940s.