This simple addition, if provided as merely an option that one has to unluck on the settings if they wish to utilise it, would make this app EXPONENTIALLY more powerful. It would unlock it's full potential in line with famous productivity books like GTD Getting Things Done - and atomic habits "micro-steps". This would great enhance my productivity to be able to break extremely complex tasks and projects into actionable next steps
Of course you have to draw the line somehwere, and even having to option to go 2 additional layers in wouldn't hurt. But at least having 1 extra layer of sub-task available as an option would BLOW AWAY the compeition many of whom already have these features.