Because we have a better sense of humor? 
Does KGS even support more rulesets by the way (out of curiosity)?
To start with excuses: Only on github there are over 200 recorded issues and we have but one developer (who I suspect has another list of internal issues). Naturally everybody cares more about different stuff, so in the end it is mostly up to the aforementioned dev to decide what is more important.
Now the jigo issue only really comes into play under NZ rules. Otherwise custom (and thus integer) komi is only possible in unranked games where the result does not really matter. Therefore the problem only really applies to NZ rules games that ended in jigo, which I suppose is rather rare (although I do know about some examples).
That does not make it right of course, but it may explain why other issues got prefferential treatement. That’s about my best guess. I can try asking anoek whether or not it might be a simple fix, but if it is more complicated than we think (reuqiring some change to the scoring algorithm itself for example) I am afraid it might still be postponed for other issues. And I actually think that it is the correct approach, being a free service (well even if we weren’t) we cannot solve all problems at once, so we should try and focus on the problems that impact the most users.