Face it, the long maul was never really good. Generally people use it for the lulz, 'cause as a weapon there's a million that are WAY better.
The recent nerfs hurt the long maul very hard. Since it's ridiculously slow (the slowest weapon in the game by a large margin) you need to make a lot of adjustments when you swing. ESPECIALLY when you overhead. The reducing turning radius hurt that a lot. Removing polestun is also a huge detriment to the weapon. Since it is so slow and unbalanced, if you hit someone who's using a fast weapon with it, they can hit you back before you can even possibly block. It's long length and heavy weight also dramatically slows you down, which makes it harder to maneuver.
For comparison, look at the stats of the great maul vs the long maul:
Long Maul
weapon length: 125
weight: 7
difficulty: 18
speed rating: 70
weapon length: 125
thrust damage: 10 blunt
swing damage: 37 blunt
slots: 3
Can't use on horseback
Crushthrough
Unbalanced
Knockdown
7,592
Great Maul
weapon length: 68
weight: 8
difficulty: 20
speed rating: 80
weapon length: 68
thrust damage: 0 pierce
swing damage: 43 blunt
slots: 3
Can't use on horseback
Crushthrough
Unbalanced
Knockdown
9,766
The great maul is heavier (more reliable crush through), does 6 more damage and is WAY the fuck faster.
I suggest the long maul gets the difficulty increased to 20 and it's speed increased to 80. It will still be slow enough to where you can outspam it, but it will at least give the user a chance to adjust for movement and to block.