I think some features are more 'tick box' - something they can brag about, tick the box as having but ultimately don't really care or support it - unless the vast majority of people use it and it keeps coming up as a 'problem' or generating a lot of negativity on social media.
I bet if they could of swept HLG under the carpet, after saying it would be updated, they wouldn't have updated the TV as late as they did. However, with a LOT of people complaining, and the negative impression on Social Media, they had to work on that. And again when it transpired that it wouldn't work over HDMI...
Recording is obviously not used by very many at all - with many no doubt using Set top boxes and other external media players for the majority of their TV viewing. I myself use SkyQ so have never needed to record any content on an external HDD. Apps, like Netflix, don't need recording either. So the vast majority probably don't use (or even know they could use) the recording feature and therefore its only a 'handful' of people that would complain and its not generating enough negativity to fix...