Pinkie Pie establishes a Theatre group, most for the fun of it, inviting her friends to help her out as a friendly gesture. The fun in theatre is that you can involve so many different talents in your play. Pinkie Pie loves involving friends.
I just recently started to write stories directly towards the FiM actively, though I have been writing for years, publishing numerous stories at Mibba and the eventual pony story, as far as to the MLP