Speed of play was one of our biggest gripes.  At high level one round could take an hour or more.  High level play in 5E can be a bit of a grind if you have people that insist on rolling one die at a time, but you can get around that.   If I could just get people to get over analysis paralysis I'd be all set. 

 I never did find a way to make 4E play much faster. 
I have to say, I've never understood the desire to go back to 2e or B/X either.  Play 5E with just PHB classes and subclasses, no feats. Maybe ignore backgrounds and skills.  Wouldn't the result be close?  That's probably a topic for a completely separate thread.
Monster lore was a bit of a mixed bag though, wasn't it?  I remember one of my first games when I asked the DM to describe the monster we were fighting and he couldn't.  All the MM had was stats - no description, no lore, nothing.  I guess that worked if it was a monster from a previous edition that you recognized, but if not you were SOL.  Monsters were just a bunch of stats and if you were lucky a picture.
That doesn't really seem to have anything to do with the edition though, more related to mod guidelines.