There should also be a clear and present difference between punishment and challenge. A lot of the games that claim they are mindless violent fun seem to have MORE fun telling you game over than "YOU JUST KILLED THE ENTIRE WORLD" they say you get to earn that screen saying you win. But instead, they just tell you to do the impossible.
If you're going to have a game that's true mindless violence the challenge should be kept moderate at MOST . . . a lot like Dynasty warriors which is as close as games really come so far to some of the points you make Yahtzee. By having huge swarms of enemies that take almost nothing to destroy but changing the formula so that their bits come off with squelches and sprays of permanent blood the game would go from blank faced violence to truly mindlessly fun gore.
I might sound like I'm being a wuss saying the difficulty should be lowered but imagine this.
A game comes out advertising mindless gore and violence advertising that it's ONLY aim is to be fun shit for people that want to blow bits off dudes with spraying blood for a few hours. Then you play it, and much like splatterhouse you find yourself watching a game over screen more often than watching the death animations of the enemies. God of War tries very hard to have mindless gore and violence, but it fails time and again by suddenly throwing instant death puzzles that have unfair timers, and enemies that swarm you but have WAY too much health to chisel through. (note: I have beaten all 3 god of war games, so no . . . I did not give up because they were difficult)
So, if you really want a game to be mindlessly fun, make it challenging to get through the game, especially the later sections, but do not make it to where chances are unless you manage to do it perfectly you will never get it.
Also, Regular checkpoints. As you yourself have said Yahtzee, it's more frustrating then challenging to be told at the very END of a section "oops you died . . . time to start over!" if there are regular checkpoints it creates a bit of space between that frustration and that fun.
The best games, keep a person in that state of pure fun longer. The more often you take them out of the action (loading screens, game over screens etc.) the faster you take the fun away from them.
Well I've rambled on enough I think. Take what you will from this, if anything. Feel free to compliment it, berate it, or completely ignore it.
And always Yahtzee . . . keep doing what you do best man. We wouldn't want you ANY other way.