I was only around during the birth of the OBSE, and it didn't have that many compelling extensions at the time (but a very long to-do list).
Can anyone care to explain what wonderful extensions came to fruition in my absence, and what sort of mods this lead to?
Off the top of my head, no. My now deceased Alienware on the floor behind me still holds all my files (as I've been a little too distracted to copy over the files yet), but I know when I re-installed Oblivion about a year ago or so, I also went online and downloaded all the mods from scratch for a fresh play through. I kept encountering OBSE everywhere I looked it felt like, and finally I caved in and got it because there were too many mods I really wanted to play that required it. However, the thing I do remember from what I read is that OBSE was needed for things that we could do in Morrowind without the need of a script extender.
EDIT: Also, I was heavily involved in modding for Morrowind, but didn't do much in Oblivion for a number of reasons, the main one being that I didn't feel like relearning the system (which was reportedly much more complicated) and I boarded the Oblivion boat pretty late in the game (for financial reasons), no pun intended. So I don't know firsthand what the differences were between the two, only what I had read.