Thanks BatfinkUK,
I felt like this had to be said, because strangely no-one (aside from one stray comment on some tec blog (I think it was engadget) which pointed me to this again) really adressed this and I think much of the whining could be prevented if everyone were aware of this.
Of course, if the Atrix 4G can ship with this massive battery, why can the Optimus 2x not, this bothers me quite a bit.
Edit: On topic (rooting) on another
Thread HustlinDaily linked to a thread in the XDA developers Forum about a system dump for the Optimus 2x,
the user, who is one lucky owner of this phone, later mentions that rooting was quite easy and could be even more simplified with some tweaks.
I think this confirms that rooting the Optimus 2x is possible and easy.