Honestly I felt the same about the first and second movies but when you compare Leader Optimus Prime from TFM1 to Buster Prime in ROTF you understand why you need to "upgrade." Another good comparison is the voyager optimus and Battle blades OP.
Having said that, I did not upgrade BB nor did I downsize to the new deluxe ratchet or Ironhide.
Recent Additions:
Robosen Auto Converting Optimus Prime
Incoming:
Canon Optimus
Wishlist:
MP Jazz, MP Ricochet, MP Waspinator
Selling:
Lots, just need to sort it out.
Looking For:
Seige Cyberton upgrade Optimus Prime