I mean, mechanically i doubt youd be able to solo an ultimate anyway if they did allow it. I havent looked at UCoB in a couple years, but i half remember enough madness going on that it doesnt seem feasible. But yeah, the if the devs want an "Ultimate" difficulty duty to always remain at least a little hard i cant say that i disagree with them. If you want a solo challenge, go after some extreme trials and savage raids.