As the OP has noted obviously you can fly the sim without a HOTAS (heck you could even do it with a keyboard or Xbox 360 controller) whether or not that's optimal is an entirely different matter. With modifiers a traditional joystick is very effective in DCS A-10C.
Difficulty in a sim varies from individual to individual. I personally do not view DCS A-10C as "difficult" if you RTFM and put some stick time in you'll be on your way (I personally was able to start the aircraft, takeoff, land, employ weapons effectively after 6 hours of book and stick time).
Guess the moral of the story is to play the sim the way that you want to play it; don't allow public opinion to deter you from enjoying the sim the way that you want to enjoy it.