To me, mature means things mature people are and immature people aren't interested in. That's different from the definition mostly used in gaming context.

I could be reading too much into this but ...

The game developers seemed to be aware that "Mature" games were really not mature, and the violence all seemed to be a more graphic version of the violence you would typically see on a children's cartoon. Beyond that there is an interesting element to the storyline where Jack is very critical of Death Watch for creating the violent spectacle, and the viewers for watching the contest, which could be interpreted as the developer being critical of 'himself' for producing the game and also being critical of the player for playing the game.

Like many games, in fact, most 'Mature' games there's nothing 'mature' about the themes of the game, it's only the fact that the violence and swearing are inappropriate for children.

If Sega really wants to reach the 30+ Wii owners, they need to put out games with Mature themes (think some Academy winning movie type theme) but (with the possible except of some sexual content) suitable for kids to watch (even if they'd be bored playing it). Not games with record holding swearing fests.

Most of "M" rated action games have nothing to do with being mature.

You use motion sensing to slash people in half, who then proceed to gush blood, all while swearing every three seconds.

You're right, I think it should be an E.

Yeah I'm pretty sure that was the point too.  It was heavily inspired by No More Heroes, and one of the developers said so in an interview.  I saw it as a mature analysis and spoof of Mature gaming, and that's part of why I bought it.

But most people will never see that, and for them it's violent for the sake of being violent.  I'm sure those people said the same thing about A Clockwork Orange.

I actually have posted that they rarely are.  On here, I saw individuals hyping the game up as if it is supposed to be some sort of high art form that EVERY Wii owner had to buy if we wanted to get "mature" (hardcore) titles.

I think he put Viewtiful Joe in a genre he was discussing that Madworld fit into.  It didn't seem like bashing to me.

And ZP guy hates the Wii.  He hates the control, and is fed up with it.

Is Madworld some sort of high art social commentary on excessive gore and violence?

The problem has been around for a while but the release of the Wii pretty much set it on fire.  

You see, a couple years back gamers saw the HD consoles (360/PS3) getting vastly more M-rated titles while the Wii was slated for a lot of E-rated titles.  Consequently, the Wii fanboys were mocked by PS3/360 fanboys and told their games were for kiddies.  Of course, they resented that treatment and responded in kind by bashing M-rated games in the form of saying that they're actually immature (completely ignoring the purpose of the actual ratings).

Today, this has grown from a simple flame war into a mindset.  People who put so much effort into bashing games rated Mature a couple years ago have drilled that mentality into themselves.  Now they look down on games rated mature and will often take time just to bash them on that rating alone.  Although, hypocrisy kicks in nicely every time a game rated mature is released for the Wii in some of those posters.  They'll be happy to brag about having mature rated games on their platform of choice while bashing mature rated games on other platforms.

Meanwhile, the people who called the Wii's games kiddie still hold that opinion though they're not as vocal as they used to be (at least on vgChartz) as they tend to get banned a lot faster than the above group.

You can actually still see a slight resemblence to the original flamewars in a post from above in this thread: 

Anyway, there's your history lesson on why there's so much debate around M-rated titles.