Ok, let me be clear with thatIf it's not that hard then why don't you do it? From what I gather 8.1 has a significant amount of system level changes over 8.0 and its not as simple to update as you would think, only have to look at the OP5 and how badly that went to know this.
If I wanted to use 8.1, I could have installed Lineage. (But I feel OOS is much better)
Also, that's why I mentioned beta 8.1 and not stable. So any bugs will be ironed out in the final release of OOS and sorry but I'm unaware of the issues that 8.1 update caused to the OP5
However, they shouldn't release any new update just for the sake of releasing something. Open Beta 37 was just an update that was unnecessary. They could focus on the 8.1 instead