I don't think I've used JDownloaded since I upgraded for dial-up. Like, download managers as a whole have become mostly useless and not even that reliable. Used them all the time on dial-up since it took so long to download, you just had to.
We no longer need parallel downloads because web servers have become much more reliable, and nothing really takes more than a couple minutes to half an hour to download so being able to pause and resume just isn't that useful anymore. Chrome and Firefox now also support stop/resume natively and it works most of the time. But again, why use a download manager when a 5GB ISO takes less than a minute to load up in Firefox.
And all the piracy long moved to torrents which also does all of that and then some more.
Distros package things by demand. There's no demand. Some older software might be in the repo because they were popular 10-20 years ago and maintenance is basically, just change the version number every now and then. And even then, Arch somewhat regularly kick out packages from official repos to the AUR when they become old and a maintenance burden.