It would be nice if the skele spawners in the nether produced more wither skeles and fewer regular skeles (or none!) I'm working on collecting wither skeleton heads, but wither skeles spawn at a rate of 1 for every 10 regular skeles, or worse. I think my beacon is a long way off, even with my looting sword. I'm just not getting enough wither skeles for a chance to get a head!
Before the last reset, spawners in the nether only spawned wither skeles, and I loved that.
I get chests and chests full of bones, string and sticks from my mob grinder, and better xp from blazes. Manually killing skeles is a huge waste of time. Going to the nether to kill wither skeles for a chance to get heads works much better. Also, it's a nice source of coal for trading with villagers as an "unlocking" trade item.
So I'd suggest that the skele spawners in the nether just produce wither skeles, like before, or at least a better ratio so that I have some chance of getting the parts for beacons I need.