Good thing they haven't removed "missing the point" from message boards. My point was that removing things from games because they are "unfun" is bad design, period. If it makes for bad gameplay, remove it. But "unfun" things are necessary, otherwise it isn't a game.
I think you might be mushing a few different meanings together, here, and it's coming across overly broad.
I mean, where I'm sitting, the point of a game is having fun with your friends, so kind of by definition you want more fun, and fewer roadblocks between players and fun.
Where it gets all confused and twisted up, I think, is that challenge - and hence, the possibility of failure - is a pretty common kind of fun that's integral to most RPGs, D&D included.
This link, posted up-thread, lays out a really solid groundwork about things that are considered fun in game design. Stuff like DoaM isn't generally about failure or being unfun or anything; it's a mechanical choice made to lessen the consequences of certain kinds of failure. Much like making mechanical choices to lessen the odds of failure, it's a way to get better at your job through spending character resources.
There's all kinds of discussion to be had about peoples' preferred odds of failure, consequences of failure, level of challenge, etc. But when it's boiled down to "someone complaining Monopoly isn't fun unless they always get Boardwalk and Park Place" or "You have to be able to strike out in baseball," it's just weird because there's nobody actually arguing anything like those positions.