Memory, space used up, redundancy, etc. I'm sure that they were wanting to cut back on biomes that don't have any real distinguishing features. It was pretty similar to the desert, minus all of the trees. I do miss it and the forest though.
I'm sorry, did they say they weren't fixing any bugs? Bugs are ALWAYS their priority, right next to optimizations. I'm pretty sure that they said part of A20 is going to be a polish and quality of life update similar to A18. If you have bugs, don't report them here. Report them in the bug reporting thread, with a detailed post. Also, don't act as a spokesperson for people who may or may not have quit the game because of bugs. If they did, well, they should have realized that this game is in Alpha and it will have bugs.