Because she has so many gosh-darn wardrobe changes and drives diorama constructors nutz!
Well now, at least every Padme figure from TPM has finally been produced. It took 13 years.
There are 16 totally unique Padme figures from the 2 prequel-sequels left to be made.
It's 2012 and the license extends until 2018 (though it could be renewed and probably will be - even if Hasbro chooses not to produce).
So are 2 new Padme figures per year feasible?
Yes and no.
Some of the following figures are not as iconic as some of her already made figures.
From TPM, we'll likely see these resculpted: [and I will NOT be buying any of these as I want NEW figures of Padme]
1999's Theed Hanger Battle Queen
1999's Podrace Arena Padme
1999's Senate Speaker Queen
20001's Theed Throne Room Queen
From AOTC, I'm sure we'll get:
2002's Arena Battle Padme
2003's Droid Factory Padme
The 2002 Pilot Padme figure might get redone as well, for an ACTION figure of her, but I'd say the odds are less than 50-50 compared to these other choices for AOTC re-makes that I listed above.
2005's Mustafar Padme
That's 7 figures away from 12 that Hasbro could feasibly do anyway.
Thus, we might only get 5 more NEVER-MADE-BEFORE Padme figures from AOTC and ROTS out of 16 possibilities.
So here's what she wore in the latter 2 prequel movies and the outfit style's status as an action figure:
Pilot - DONE - 2002
Palpatine's office / Padme's apartment ??? (1)
Nightgown/Kohoun Attack/ Naboo Balcony-with blue outer robe ??? (2)
Packing to leave Coruscant ??? (3)
Refugee Disguise / Meeting with Queen Jamilla - DONE - 2011
silver outfit, deleted scene w. Naberrie family ??? (4)
kiss on the balcony / backless dress ??? (5)
yellow waterfalls dress ???(6)
black leather temptation - DONE - 2007
Tatooine Travel - DONE - 2003
Lars Homestead ??? (7)
Shmi's funeral / droid factory - DONE 2003
Arena Battle - DONE 2002
Wedding - DONE 2003
So for the 3-D release of AOTC, which Padme(s) will it be? The "iconic" looks for her that were never produced yet (indicated by my numbers) are (1) Palpatine's office and (6) the yellow waterfalls dress - either which would look really good carded. The nightgown is not so far-fetched. They made her in a nightgown for ROTS with the Padme Evolutions 3-pack. However she was pregnant and did not include the outer robe (would have to be cloth), not to mention the kohoun creatures originally shipping with the 2002 Electronic R2-D2.
So there are 7 AOTC Padme figures left to be made (and how many freaking Arena figures of her do they need to do?!!! - an improved one from the action scene could be issued for Saga Legends, but not take up regular line space). I would say 2-3 of her next most iconic AOTC figures could be made for the Episode 2 three-D release. That would leave 4 left for future years, with the packing to leave for Coruscant eventually being a smart choice since she wore this look in the Gennedy animated series as well (a variation of it).
hair in buns from Coruscant Landing Platform (1)
nightgown - DONE 2009 Evolutions
black dress - "something's happening" (2)
gold dress with head wrap (3)
Ruminitions sequence (4)
blue dress with gloves - Anakin leaves for Mustafar (5)
Senate silver - Birth of the Empire (6)
meeting with Obi-Wan (7)
Mustafar - DONE 2005
Birth of the Twins - (8)
There are 9 ROTS Padme figures left to be made (and I'm sure Mustafar will be re-carded, but they could do that in Saga Legends). Her ROTS choices are far less colorful and appealing. The (6) Senate silver one is probably the next most important to make. I'm not sure if Hasbro will do "birth of the twins" - plus it's so plain and similar to her other white-clad figures or Leia's white dress. The funeral figure is grim and also questionable. I think the blue dress with sleeve gloves from when Anakin leaves for Mustafar, as well as her hair-in-the-Leia-buns-look from her first appearance are the next best choices after the Senate. Both the Senate and the blue dress figures would look very good carded. The gold dress figure "Hold me like you did by the lake in Naboo" might also look good, and similar to the Padme Refugee Freighter figure that's shipping currently.
I could eventually see most or all the AOTC Padme figures being made. I'd have my doubts about the ROTS ones.
But we should definitely see at least 2 new NEVER-MADE-BEFORE Padmes from AOTC (Office/Apartment, Waterfalls) and 2 or 3 figures from ROTS that were NEVER-MADE-BEFORE (landing platform, Senate, blue dress).
Those are your 5 all-new Padme figures for the next 6 years unless they include new figures of her in multi-packs, not counting 7 probable re-sculpts of figures us veterans already have (like Arena Padme).