Everyone has their own opinion, and if removable batteries and SD support is what you need, then as many have said here, there are other options for you - and great options at that! I've had numerous phones with removable batteries and SD support and my experience with it is this - 1) the removable battery is nice, but I RARELY, if ever, swapped the battery and it really only served for peace of mind if the battery somehow went bad; and 2) I've had more than one SD card go corrupt causing me to spend many an hour deleting files that were so corrupt that they would lock up my computer when I tried to open them, I was forced to splice together some videos to remove the corrupt part (including one of us singing to my daughter on her first birthday), and lost numerous pictures of family events thanks to the SD card going rogue on me. I've had less issue with non-removable storage, in my experience (mostly Nexus/Moto devices and iOS devices).
I'm not saying that these things don't have some utility in the tech world, but c'mon, are you trying to tell me that a bunch of us on here have more experience in this sort of thing than Samsung? Hell no. I'm sure they did their research, and the average consumer doesn't need the swappable battery or SD card. I know my wife won't care as long as she has enough storage on her new S6. And she's probably in the majority group - which is what Samsung is targeting. People here are really the tech minority, whether we want to admit it or not. I'm perfectly content, and actually ecstatic at the idea of picking up an S6 or S6 Edge and can't wait for this to be my next phone.