This is just my opinion that PhD thesis should be the compilation of research papers with brief report instead of 100-200 pages report with detailed information. Generally the thesis contains all the information that has been published in the form of research papers. Then why not we bind all the published papers along with brief report and mark it as thesis.
Also when we publish any article most of the time we consider already published research papers rarely theses. This not only saves time (to do other academical/research activities) also saves paper and economical (as I have seen lots of paper and money involves in writing thesis).
This is just my observation. May be I am wrong in my opinion, I highly welcome the experts opinions. Thanks.