I also prefer the previous Markdown editing mode. As mentioned above, it should at least still be accessible to everyone via the toggle. They've just made the new rich text editor mode the default.
Although this isn't a super strong opinion: There might be some value to the admins setting the old way as the default.
I've noticed that especially users new to this community often post code without using code blocks.
Before, that was merely harder to read. But now, if that code is full of automatic pretty quotes and ligatures, it might also be tedious to fix up when copy-pasting into DrRacket or whatever.
(Sure there probably exists for Emacs, or I could write myself, some un-prettify command. But not everyone uses Emacs. Shocking, I know, right? )