So playing in a casual manner automatically equates to not wanting a challenge...
No - rolling for attributes has nothing to do with challenge, it's just random handicapping or overpowering. That's not challenge - that's dumb luck that applies to the whole game instead of just one action or plan.
Hmmm, there's something a little off with that logic. I play MW3 casually, but I play online for the challenge more experienced players offer because I find it fun...
I have no idea what "MW3" is - some sort of FPS computer game, I guess - but playing against more skilled or experienced players is a challenge; playing with your shots randomly misfiring is just making things arbitrary and frustrating for yourself and everyone else.
Your whole argument seems to be predicated on the "fact" that rolling for attributes assures failure. that's not a fact. It's not even a fact that majority of your attributes will be low...
Of course not; it's a crapshoot. Pretty much literally. You are choosing to have the effectiveness of your character for the whole event randomly either overpowered or nerfed. Failing on one rolled-for task in an evening is fun; so is getting the randomly powerful guy for the duration. Getting saddled with the doofus for the session is not so fun, though - except maybe for your sadistic "friends".
the point is that some people find fun in the challenge of taking an underdog and having him succeed
So let them choose to have a low powered array. If that's really what it's about, then at least do it by choice, rather than by random chance. Does the guy who rolls low really get asked if he wants to be "doofus for the day"?
Is the reason it is hard for you to grasp what might be fun for others... or even what other playtyles exist because you've only experienced a very narrow range of playstyles??
There's really no need to resort to ad hominems. I have played many, many playstyles over nearly 40 years of roleplaying; that's how come I know of a few I really don't like (as well as quite a few that I do).
The style preferences are also often game specific. The style I described, for example, works quite well in Call of Cthulhu; it just fails miserably, for me, in D&D. CoC really is all about your character's descent into madness and death; D&D doesn't bill itself that way.