Why waste effort trying to support users who have **** graphics cards?
The no1 reason...
The more machines your games run on the more potential customers you have.
Now, some other common "things"...
People with old cards / machines dont play computer games
Many authors who make there living off shareware will tell you otherwise. Old machines are still out there and being used to play computer games with. Just not the triple A type.
Just tell them to upgrade there hardware!
People are lazy, they would just go else where for there fun. If there not lazy, then there scared or unwilling to spend extra money to do it. "Esp for a shareware game"