How exactly am I to go about this, outside of putting an impassable barrier between the opponent and the PC's everytime I want the guy to have a good "Mwahaha!" moment. And it really takes people out of the moment of kicking in the door in a dungeon when the bad guy goes on a "I am the Bandit King, hear my lamentation about my sucky life!" rant. Try to think for a second how a scene like that would look in a real life fantasy dungeon scenario. No, not actual "real life", but try to imagine yourself as an adventurer in a party, you kick in the door to a room and the chief cultist tries to stop you with "But wait! I need to expound on who I am and what I am doing here!".
Yeah I hear that - after having the 'charge' happen enough I finally just made a table rule that my players were happy with:
Rule: When fighting a BBEG roll initiative and unless you get a surprise round combat will hold and any and all role playing that the GM wants to happen will happen - this will not alter the initiative count - change positions of anything, or anything else like that.
This lets me do a 'expound' if I want to - and play it as the bad guy would in terms of verbosity - some bad guys just attack - a few (especially if they have a plot clue or red herring to toss) might just say something.
The players have seemed ok with that - about half the table wants to just 'ATTACK' and the other half wants to talk so it was causing table tension as well - this seems to have hit the right mix - as the 'ATTACK' crowd seemed to worry more about loosing tactical and position related advantage by waiting around for dialog - so by rolling and freezing movement it takes that fear of 'getting the drop' away.