2010 Jōyō kanji and (lack of) simplification

Hi all,

I am currently going through all 2,136 Jōyō kanji and have found an odd phenomenon whereby certain components were not simplified in 2010 additions as their shinjitai counterparts were.

Compare 煎 and 前, where the official Joyo version of 煎 appears to have the meat component and 前 has the moon component. Also compare Jōyō (but unsimplified) 剝 and hyōgai (but shinjitai) 剥.

By the way, I understand that, in the day-to-day, these differences don’t make a huge difference except maybe to government workers and newspaper editors, but I do find it strange that the 2010 Jōyō additions favored (and codified) kyūjitai components over well-established shinjitai alternatives. If you could provide articles that explain why that was the case, I would greatly appreciate it!