Personally I think that did more harm than good. It effectively removed B Ranks from the picture, leaving players with only A and S Ranks, in short, it pushed more people into A and S Ranks and exacerbated the problem.
The solution is a viable alternative to Hunts which rewards Allied Seals and can take the majority of the heat off Hunts. If Hunts were just another source of Allied Seals, rather than the sole source, people would be much less caring about their fate. They'd still remain open world content, but they could be enjoyed the way they were meant to be, rather than being a massive zerg rush.
Leves would probably be a really good way of dealing with the issue. Add a small sum of Allied Seals to Grand Company Levequests and a larger sum to regular ones if you defeat the notorious monster which they can occasionally spawn with (more Allied Seals because that's a purely random factor). Overall there should just be more ways to go about getting Allied Seals. More Hunt mobs themselves (I think 1 S Rank, 2 A Ranks, and 3 B Ranks per zone would have been good) would help, as would an instanced Guildhest version of the mobs, where they can actually have mechanics and be designed well. Having everyone go after one source of Allied Seals is the major problem here.
