The purpose of the rules

[Max_Killjoy]

If person X should automatically succeed, they shouldn't have to roll at all. I'm not fond of critical fails for skills (or critical success, for that matter).

I tend to agree that there comes a point where a roll is superfluous (thus "maybe even to the point that they automatically succeed") -- or should only be made for degree of success, not chance of success.

And in general I'm not much of a fan of "you fail no matter what on this result" rules unless they're handled very carefully.

[Pelle]

To expound on the part in your first paragraph -- if a game using this system does end up with a character who is a superhero or demigod (and thus possessing or able to access fantastic strength), then their attempt (roll, whatever) will be able to easily overcome the DC of a normal door, maybe even to the point that they automatically succeed.

Yeah. I'm running a 'well known' d20 system at the moment, and try to mostly follow this approach:
http://thealexandrian.net/wordpress/...and-difficulty