https://powdertoy.co.uk/Wiki/W/Previously_requested_elements.html#CMND
>Rejected - lua commands could be dangerous and contain viruses.
yes you don't want malicious people giving you a script or command with something like os.execute(shutdown \a) when your doing school work or os.execute("start http://listen.abacus.fm/abba.m3u") that runs every tick so you get spamed with windows(in which i've tried and is not cool)
1. Lua can contain viruses
2. People can make laggy saves that spark hundreds of blocks at the same time or go something like !set life deut 999999 and blow it all up while commands are running
3. It would be cool!
Which is what the community will do, to add command-block like features...