Upgrading a PS3 hard is incredibly easy. You didn't have to dismantle the PS3 or anything. There was a plastic cover over the drive cage. One screw released the drive cage from the PS3. You pull out the drive cage, remove the old drive (4 screws), and replace with your new hard drive. Then put it back in like you found it. The whole process takes less than 5 minutes. The software then formats the drive and you are done. Pretty painless.
I don't know if I can make a case for it actually being "encouraged" for users to make the upgrades. But it is in no way discouraged. There are detailed instructions on Sony's support pages that are just a Google search away.
I find the easily replaceable internal drive a much better solution than external hard drive support. Yes external support allows for larger cheaper drives, but I just don't want crap hanging off my system. That means more cord mess from USB and most likely an A/C adapter. I also like to move my consoles between different rooms (or to a friends or family member's house) often, so once again external drives would be a hassle.
I'm happy to know that the PS4 drive is just as easily replaceable as the PS3's. For me, this is just another thing that solidifies my leanings towards the PS4 as my console of choice. I'll be upgrading the drive day one once I get one.
My two bits.
Thanks for the show.