Never recently, but when I was a kid (like... 13 and younger or so), I did it a few times.
Paper Mario: The Thousand Year Door - Same story as everyone else. Loads of text before the fight. Easy first form. Loads of text after first form. Very strong second form. Just didn't feel like trying any more after a point. I'd very much like to replay it sometime, being (much) better at RPGs and character building now than as a kid. The badge system in those games seems like a lot of fun in retrospect.
Breath of Fire IV - I got all the way up to the final fight and couldn't even beat the first form consistently. I did so once and absolutely could not get past the second form because I was severely under-leveled and refused to grind more. In retrospect, I have no idea how I got that far as a kid. I ran away from most random encounters, didn't pay much mind to some of the late game combos, and just bashed my head against bosses until they died.
Super Mario RPG - Summer break as a kid. Got up to the final boss, wasn't having any trouble with it, got called up for lunch, and after I just kind of... never got back to the game. I really don't know why. Never felt like it, I guess?