One thing still under speculation is how one could effectively suggest artificer rune arm use to be possible without multiclassing into artificer.......... this one is pretty complicated as Cordovan himself stated that the code for runearms isn't fully understood and when they design a new rune arm they just copy and paste already existing code. The closest candidate for allowing a non-artificer to use a rune arm seems to be the Half-Elf Dilettante for artificer, but apparently, part of the code involved for restricting rune arm use to just artificers exists on the runearms themselves rather than just being in a feat you get upon reaching your second level of artificer. In other words, they'd have to sort through all of the code associated to both runearms and the artificer class and actually understand the full purpose of each piece of code in order to determine what would need done to make runearms usable. I'd think that them contacting the original author of that particular piece of code and paying them to help improve the racial tree enhancements for the Half-elf Artificer Dilettante so it could include such would be simple enough, however I am ignorant on the identity of the author to said code and suggesting them to get a hold of said person/persons may or may not be suggesting that they either resurrect someone who has already died or asking them to deal with someone who'd ruin their company through greed or incivility and neither are ideal while the first is simply impossible. In the end, writing the code for an imitation rune arm (Using some of the code for orbs) from scratch and simply leaving out the restrictive code while claiming the item grants you proficiency with it if you took/have the magical training feat and placing said item in the Cannith Challenge loot option might be the only viable option, and coincidentally this also solves part of the orb dilemma in which the rest could be solved by randomly generated orbs that can be disjuncted and crafted onto.
Anyhow, this is just as I understand things I suppose I could have misunderstood some of what Cordovan said, but if that is the case he can perhaps explain such in greater detail?
He may have meant that he and the other socially active devs don't understand such....... but, either way I'd like to speculate further on the possibilities here for the sake of building on the understanding required for making a realistic suggestion towards improving single weapon fighting outside of Artificers and Bards (But in this case also for bards wanting to use runearms).