My 2.1.2 doesn't have that options checkbox, but the rich editor is there. However, when I upgraded I simply deleted all of the old files and dropped in the new ones... I didn't overwrite the old ones.
This'll sound stupid, but it's what the WP forums will tell you first (I know, 'cause I read that alot over there <g>) -- clear your cache and reload. :)
Oddly enough, the WYSIWYG editor in my WP stopped loading today, but I managed to locate the toggle to turn it back on:
Admin > Users > Your Profile
The very first option right under the page header is "Use the visual editor when writing". Somehow it became unchecked since I last posted. Checked it, and everything is back to normal now. Take a look on that page for your install, and see if that option is there and checked.