In my opinion, OE is to blame. Yes LA gave them a contract to do it in said amount of time and money, but it is OE that was unable to deliver. They should of asked for more time and money in the ORIGINAL contract. They are fully to blame for the poor state of its release. LA might have put forth an unreasonable timeframe/pay for the contract but OE accepted it. It wasn't forced upon them...
Quote from a Chris Parker interview:
Chris Parker: We had an extremely aggressive schedule on The Sith Lords. We first started talking with LucasArts about the title in June of 2003, but at that time, we had NEVER SEEN the game except for information that was available to the general public. We signed up for the project in August and entered production, while still working on many pre-production tasks, in October of 2003. At the time, the ship date for all versions, PC and Xbox for all languages was November of 2004. Of course, it was only by that time that we really understood we were making a sequel to the game of the year for 2003 - and that really upped the pressure on us to deliver. It was around then that LucasArts decided we'd probably want to ship some of the versions in early 2005. In May of 2004, we had a great E3, and that solidified our need to ship the Xbox for Christmas.
http://rpgvault.ign.com/articles/575/575166p3.html
From this it doesn't look like LA rushed them at all! They actually gave them an extra month for x-box and an extra 3 months for pc.