A few months ago we switched to Closure Compiler for minifying JavaScript code. That post explains a small number of differences with the new minifier and advises plugin developers that they may need to make a few simple changes to support it.
Minification isn't essential, you can still publish unminified, and it would probably still be difficult to cheat or reverse engineer the game. Minifying is an optimisation (reducing the script size), and just raises the bar even higher for cheating/reverse engineering - but still doesn't make it impossible.