Beta is just part of the life cycle: Software release life cycle - Wikipedia - one step in becoming more stable and feature rich. Release is a point where usability is deemed sufficient. With an OS I’d say it’s both bugs and incorporating all the various interlinked versions of different software together in a working way. A software is never quite finished…
For temporary fix to get more up to date software, take a look at unofficial backports (both using byzantium as base, or crimson), both have forum threads. It’s something that @galilley has set up as a hobby.
Other option is to wait a month or two (hopefully not longer) to get the real new PureOS official Crimson release, to get the goodies. Perhaps even get the beta, if/when after we get the word that upgrade works (so you don’t have to do a clean install).