thank you for your questions and contribution here. We looked into this in more detail and there are some topics which have to be considered with the total pages.
It looks like an easy thing to sort the column "Total pages" when it is displayed, but unfortunatly there are some cases where we do not know the number of pages. E.g. if you drag and drop a file to the document tray the initial number which is shown there is "1+". This will change after some time or when the document is viewed. But for some files we are not able to calculate the correct number of pages and then the total pages remain with "1+".
Simply ordering a list, which maybe has not the correct data, might lead to confusion. We are currently thinking about solutions to this issue.