I'm going to be the voice of dissent (or the exception to the rule) here and say that my ROTS Battle Droid stands just fine on his base. The plastic is crappy and his right leg is warped, but I'm able to put his left foot on the peg completely and kind of "bend" his right leg a little to the left and a small piece of the terrain holds is more or less in place (not securely, mind you). He looks pretty cool standing like that, so I'm happy with it.
This is not to say that the quality of the figure overall is not pure crap though. If a figure it more or less a skeleton, you'd think you'd want to use the highest quality plastic you could to make sure the figure wouldn't deteriorate over time. Unfortunately, as usual, "If something's hard to do, it's not worth doing" seems to be Hasbro's mantra these days.
I still say the POTJ Security and Boomer Damage BDs are my favorites that have been made. They have the film accuracy as far as the thin legs and arms, but also have a higher grade of plastic than the bendy crap that Hasbro's using on them these days. I've actually had more problems with my TPM BDs bending in their lower legs than the POTJ versions.
And, for the record, RELEASE THE TROPHY EDITION OOM-9 ALREADY! You don't have to do it as a Trophy Edition as it was originally conceived, but jeez, Hasbro, the TPM version sucked and now is pretty much your last chance to do it and hope that it will sell more than three figures nationwide.