Other than logging (journald is one of the few truly core systemd components), these are all basically independent programs chosen by your distro. As such, each is best evaluated independently. Let's give it an honest shot:
- resolv.conf: systemd-resolved is not unique here in providing a stub resolver and not just NSS functionality (it's been years, but isn't unbound often the same way?). And if you want to have systemd-resolved but not have its stub used in resolv.conf, you're free to do so! Just remove the symlink that is /etc/resolv.conf and replace its contents with whatever you choose.
- cron: systemd timers provide an alternative to cron. You're still allowed to create cron jobs and use cronie (or whatever traditional cron implementation) you like.
- ntpd: leaving aside the fact that most distros (I think?)
nowadays use chrony rather than ntpd or systemd-timesyncd, you're likely free to switch to chrony or ntpd depending on your distro. Afaik, this isn't a daemon with deep system integration, and you should be able to plug-and-play without much issue.
- network configuration scripts: What're you comparing systemd-networkd to? NetworkManager? Debian's ifupdown scripts? RH-family's network-scripts? In any case, network management systems tend to be pretty pluggable (much like in the case of your cron daemon). You can even have them live side-by-side, managing different interfaces, e.g. have NetworkManager do WLAN, while systemd-networkd does Ethernet interfaces.
I don't know any of the story behind timedatectl, so I'll avoid opining on that one.
But generally, it really seems like each of these components is as pluggable and freely-choosable by a distro as one could reasonably hope for. And, like you acknowledge, they end up likely getting chosen because it's easier for distro maintainers. Which is kind of a big deal, imo. But if you don't like your distro's choice, it makes sense to complain to your distro.
In general, I think your suggesting that these new-ish (most of which are no longer very new) components were just made for the hell of it, I'd encourage you to look a little deeper into what they offer compared to the incumbents. For starters, they generally work together pretty cohesively, e.g. systemd-networkd and systemd-resolved do some mutual coordination stuff that's pretty nice. Systemd timers have numerous nice properties compared to cron. Etc.
Again, you (or your distro) are free to take or leave these components, since they can be picked on their own. But an analysis of "these new components from the systemd project 1) are forced on me, 2) exist primarily for the sake of change" seems both incorrect and uncharitable.