what if you want to compete in a sport? training without rules is useless for that.
a striker who knows how to counter takedowns is in fact a grappler who also has striking
an armed guy is very dangerous to anyone who is not armed
and bjj is ideal in a cramped place, it's used pressed up against the other person there IS NO MORE cramped then that.
you don't know why people are excited with bjj, let me ask this how much time have you spent training in it?
if the answer is none or very little of course you don't know why people who do it enjoy it