The article has all the juicy details, but the important facts are:
Ran out of space.
Implementing packaging (yay for buying RBB in the store!)
Room for more barrel aging
Rooms for quiet seating and for TV viewing and music
Russ and co. were limited in space when they started. I really liked the place and was always bummed to not be able to make it up to TC more often to stop in and have a drink. I hope they don't plan on packaging the "regular" beer. Personally, RBB is what it is due to the eclectic brews they make. I hope they can manage to get some interesting stuff in bottles/cans.
They have video web series chronicling the move planned on their website.