Your loss, in fact!
By neglecting software State Machines, you are omitting a very powerful tool from your armoury (to mix metaphors).

State machines are de rigeur when it comes to implementing comms protocols.

Many of the control functions commonly associated with "small" microcontrollers like the 8051 are extremely well suited to state machines; eg, consider a VCR:

The events are, say, Tape Inserted, 'PLAY' button pressed, 'FAST-FWD' button pressed, 'EJECT' button presseed, etc;
The States are, say, Idle, Ready, Playing, Spooling, Ejecting, etc