Full disclosure: I adore The Patriot. I could watch it a hundred times and still love it with a totally irrational love.
That said, why does Gabriel have to die? Thomas has already died. In front of his father and siblings. That's pretty heart-wrenching. That's totally enough to make Mel Gibson go bat-poo crazy and slice and dice some redcoats.
I'm just saying that I am already sufficiently emotionally manipulated by the film, and don't need to see Gabriel die for the simple and sole reason that he is an idiot. Thomas, at least, was trying to die for something. Gabriel is just dumb.
I know, I know, lost cause, blah blah, final battle, blah blah, carefully mended flag, blah blah blah. He doesn't have to die!