IMO there should be less in base. No server software except for sshd.
I mostly agree. Base should contain all the software that is required to make a minimal but functioning computer. The question here is how to define "functioning". Today, a computer that can't be networked is mostly considered useless, so we need the basic TCP/IP stack, we need setup utilities (like DHCP client and configuring the hostname and resolver).
A computer that can not be accessed is pointless and might as well not exist. In the old days, that meant that you have to be able to connect a terminal to the computer, often by serial line. Starting with the IBM PC era, that was replaced by connecting a video monitor and a keyboard. Today, a large fraction of all computers no longer have physical console connections (they are in data centers, or virtualized). So sshd is absolutely needed, as it is often the only sensible way of getting into the computer. Technically, sshd is a server (in the networking sense), but in the practical sense, it does not provide a service to other machines.
Remove the MTAs, remove NTP, remove the KDC.
Here I disagree. Within a modern Unix system, minimal functioning email is required, even within a single computer. The one example already mentioned is storing results from cron job. I think base needs to contain at the minimum a simple and preconfigured MTA and MUA. Whether that has to be sendmail or not is something worth discussing, although I come down on the side of wanting sendmail present (even tough I personally don't use it on any machine).
Similarly, in a modern networked world a computer whose clock is off is just a nuisance. A minimal but functioning NTP client needs to be present in base. That does not mean that base needs to contain a full-feature NTP; for example the capability to connect to hardware clocks (such as GPS receivers) or being an NTP server is not required for basic operation.
Cron and syslog are more examples: A basic version of both is needed for a simple system to function sensibly.
I vote for "oksh" in base.
Why? We already have a good functioning korn shell in base. It has been there for many years. In the case of shells, removing them from base is very dangerous, because there is a huge installed corpus of scripts that rely on the features of the base shell.