But i really see that koboldKare doesn't have fully done Core for now, and slowin' down fixing and improvin' game is bad omen.
AFAIK the break in updates overall were due to the dev being busy with moving to another location and all - so I personally do still expect bug fixes and considering that he still plans to "support" it for as long as he manages, meaning include bugfixes.
Considering that he's (atleast from last time I checked) also okay with including certain user-content (scripts and such) into the base game after ensuring it works and all, so their mods can have more than just pre-defined functionality... there's still room for new things from the modders-side
As for a fully done core, I believe that's mostly subjective, as quite a lot of people enjoy it being so "barebones" for RP purposes and all (though I might've misunderstood the intended definition of core here).
But yes, I do agree that there's still a lot of untapped potential, however, one shouldn't forget that he did work on it for a long time and whether we like it or not, everything has to see an end, even if just for the time being - who knows, he might return to it fully or start another project in the future with similarities to this one with more focus on "gameplay" rather than a sandboxy approach (unsure how to phrase it, so this'll have to do) and yes, with "gameplay" I refer to most requests/ideas I've seen with people expecting some form of progression aside of more of tutorial-ish tasks and such.
As for keeping it similar and just adding more things to do of sorts - modders could still do that.
However, that'd require them to make a pull-request to code-based content of their mod(s) for the dev to check over and all - but AFAIK (last time I checked at least) he was still up to do such things, so long as they don't conflict with the base and just get enabled via their mod or something along those lines.
(As for why not to include a possibility for custom scripts in mods was due to security concerns IIRC - though I might remember wrong)
Also sorry if I do come across as aggressive - that's not my intention, just trying to share my opinion! (But yes, I do agree that it could theoretically be improved a bunch and "could be" something even better, though my "rant" is more about calling it dead or abandoned, which is quite harsh for indie games that achieve their intended goals - as that'd indicate it not being achieved at all)