I believe the addition of the bizarre plane would cater to audience who has interest in simulation games (IE Sims/Breath of Fire II Village recruiting). It adds quest points and collectibles for perfectionists. I do believe that, since it's an addition, it's more of like an option/not related to the story line. IMO, it won't break the immersion as you've stated as long as you avoided going to such place. Generally speaking, immersion with realism in mind in a fantasy game is out of place.
As they say, it all depends on the eye of the beholder. Let's just get the 1M as a compromise!
TL;DR the Bizzarre plane is a nice addition.
