I love it when people start a post by insulting my username.  It really sets the tone of the conversation... as well as the maturity level.

Also, we've now moved our goal posts from unexpectedly painful things which you are given no indication of during the initial gameplay to unexpectedly unavoidable painful things which you are given no indication of during the initial gameplay nor demo or other source.  Well done.

It's about trial and error with painful consequences.  Some games tell you in the manual.  Some games tell you in the intro video.  Some games don't tell you at all.  You find out by trial and error (as was intended) or reading about it (strategy guide/faq/etc).  Goodness help us if the game surprises us and does something unexpected let alone force us to think outside the box and find a different solution.

In the end, it's a matter of degrees.  In Mario, you die, you lose a life, you start the level over.  Lesson learned and the game goes on.  In an RPG, you might take some damage or you might have to restart from the save point which is convenient located right before the boss that just hosed you.  The game goes on.  In a Rogue-like game, you drink an unmarked or mislabeled potion and you die.  The game is over.  There severity of the punishment in Mario and the RPG isn't very high.  The severity in the Rogue-like is maximum.  The thing about is that once upon a time, this was acceptible.  Many games were about pattern memorization and the like.  It was part of the game.  Something messes you up in Mario or Megaman, and you memorize it and come back to beat it.  Today, gamer tolerance is far lower.  Gamers demand "fair warning" and cry when the game unexpectedly does something awful.  "Gosh, those developers did that and it was so unfair, they're such bad developers.  Shame on them!" 

To each their own though.  I grew up with games where the developers did all they could to challenge you.  Those games were sometimes frustrating but they were fun too because that challenge made the victory all the sweeter. 

Of course, some of them are even funnier to watch than play:

@WoW

The initial tone of my response was largely set by the tone of your first response. Apologies if that offends you, but perhaps in the future you should avoid trying to counter an argument with reducto-ad-absurdium examples. They're barely a step above making blanket statements and enforcing stereotypes to justify your beliefs.

As for the concept of game difficulty (which is what you're trying to get at), you're right about one thing: game difficulty is not inherently a bad thing. But you have completely missed my main point, to a degree that's astonishing: the means of introduction of a challenge DOES matter, immensely.

Let's return for a moment to Super Mario Bros: none of that game's challenges are unprecedented; you watch the attract mode, and you know exactly how the game plays. It never tries to pull a fast one on you later by changing up the rules or asking you to perform at unreasonable levels of precision. The game is still pretty challenging in spite of that, of course, but because of scale instead of trickery.

And now let's look at something on the dead opposite of the spectrum, Super Mario Bros ROMhacks. You've shown a lovely video of one, in fact, and it just shows how easy it is to fail even when everything is already in place to avoid it. ROMhacks are notorious for adding in entirely unreasonable challenges, like having to do an absolutely perfect run of the levels. They also love to present you with invisible traps (the old "invisible coin blocks to make you fail at a jump" trap comes to mind), unforseeable and unavoidable enemy drops (warping right up a warp pipe onto a Goomba), and punishments for not going the way they want you to (like the ROMhacks that require you to jump the flagpole, or Mario falls into a pit when he jumps off the flagpole).

Super Maro Bros could have been an arcade game, the difficulty was so well-tuned. And in fact, there were actually quite a number of PlayChoice 10 arcade machines with it on there. But those overkill ROMhacks wouldn't last a month in an arcade; nobody would plunk a single quarter into them after their first game, unless they were particularly masochistic. I'm a strong believer in the Arcade Test, too: if a game can't survive in an arcade, then it's doing something wrong. And I can't think of many RPGs that would survive the Arcade Test...