Just trying to think of this more in depth... if the draft came first... their would be a lot more teams pressuring players to resign for the draft and players wanting to wait for FAs, causing a lot more feuds.
Also the draft coming first would drop the veterans market price, which could help teams that don't spend as much on FA (like the Packers), but it most likely also have a lot more players overvaluing their market (like DL Cullen Jenkins and WR Greg Jennings both reportedly did, which according to rumors, led them to turning higher offers from the Packers during the year, then they ended up getting on the FA market), which again, would led to even more veteran feds with teams.
The draft coming first would help rookies, but hurt vets. Teams could make big mistakes or take advantage either way. I think teams could do great or horrible either way... if they make wrong assumptions with the first one, it can screw them on the second one.
Like this FA or draft pick fixes that position, when it doesn't... and then they don't back it up with the other.
Overall I like it the old way, FA came first, then we had a two day draft, with 3 rounds on the first day and 4 rounds on the second day. But that's history.