The current picocom version is 2.2. In ubuntu repos one can find only old (outdated) version (1.7).

If you report a bug and the security and bug fixes are significant then the package will be updated sooner.

Just because a newer version is out doesn't make it "outdated" as long as the version is supported upstream. If the gains in the new version are slim then the package will remain.

Ubuntu is not a rolling release and packages will remain on "old" versions as stability is champion over getting the latest packages into the repositories.

Most packages in Ubuntu come via Debian, and as far as I can see from https://packages.debian.org/search?keywords=picocom&searchon=names&suite=all&section=all also Debian is only on version 1.7

I suggest that you create a bug report (both in Ubuntu and in Debian) to request a version upgrade.
I assume that the list of improvements and bug fixes https://github.com/npat-efault/picocom/releases is ling enough to justify such version upgrade.

(Remark, there is already a bug report in Debian requesting a change for a single item provided by the new version https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=837046 )

Please try this install procedure:

https://mark911.wordpress.com/2016/10/06/how-to-compile-and-install-newest-version-of-picocom-minimal-dumb-terminal-emulation-program-in-ubuntu-16-04-lts-64-bit/