I think this MUST have to do with some specific players. I play BRD's from my home-built "home theater PC", and it does "pause and play" just fine.
No, it is not the player. It is the disk format. The newer format, called BD-J (Blu-Ray Java), does not allow resume, on any player. Some of the older blu-ray disks were created before BD-J. The great majority of all BD disks are BD-J. You must have gotten lucky and used an older BD disk.
Here is one site which explains this. http://www.sony-asia.com/support/faq/432547
Why can’t BD-J resume play?
Resume play won’t work because BD-J application in the disc disables the resume function. The Java software controls playback plus all the interactive content (like what Windows OS does on the computer). When you hit stop, or turn off the player, the Java application on the disc reboots in the next playback. This results in resuming playback from the beginning of the disc. Therefore you should use pause instead of stop for Blu-ray disc that supports BD-J application.