I whole-heartidly agree that a good plot is always neccessary for a more story telling oriented game like an RPG.

I'm more specifically referring to "mindless shooters". A game like R-Type, Raptor, SmashTV or Contra. In those games, you more or less are told "aliens are trying to kill you so kill them first" and that's the entire premise / story.

Will these games be hurt by having a plot? Or as long as the "chaos factor" is perfectly implemented, everything else on top is just gravy?

A story provides an explanation for why things are happening in the game world. Sometimes no explanation is needed - take sports games, for example. Do you ever wonder why these people are tossing a ball around? No, so there's no reason to go into a big long story about how Character X made it to the big league. He plays baseball, and that's all we need to know.

If "kill them before they kill you" is enough to get people shooting, than leave it at that. It just depends on your target audience. Seeing as how you called it a "mindless shooter", you're not aiming for people who would wonder why the aliens were trying to kill them.

Rpgs do not necessarily have to be story-oriented in the sense that they would necessarily need a linear, pre-written story (provisionally, see below). The actions of the player's character already form a story by themselves and the game world will restrict the player's freedom to make the choices, so in a sense you do have a story at the end of the game anyway. If the game forces me to save the world, cure the plague, and kill the big bad chaotic evil dude — again — before the end of the game, what choices have I made? Not really much, considering that saving worlds, curing plagues and killing big bad chaotic evil dudes are rather epic accomplishments that make all other activities pale in comparison.

Of course, your opinion can be different dependin on whether you consider the rp in rpgs more like playing a role in a play or more like playing a role of a character. The former requires a more or less pre-written story, while the latter requires the concept of the character and the world he lives in. The former is about hearing a story while the latter is about telling a story. Some people want to hear stories, some want to tell them. So I'm not saying rpgs really can't have a story (again, in the sense of being a pre-written manuscript for the players to act through), just that it is not always vital. Now, personally I've heard too many messianic stories of lawful good amnesiacs curing plagues in rpg form already, so I want to start telling my own stories for a change.

I'd still like to emphasize two things about cinematics (and similar game-interrupting non-interactive sequences):

1. They should indeed be skippable, which includes not only the fact that they should not contain vital information, in the sense that those who skip them aren't totally lost. If someone skips the cinematic, at least some sort of summary should be given about the information in the cinematic. Also, skipping should be an option from the game's options menu, so that I don't have to press esc or whatever every time a cinematic starts. This should apply to the beginning animations of the game as well, in my opinion.

2. As some people do not enjoy watching the cinematics, they should not serve as rewards per se, because those who skip the cinematics can be disappointed for getting nothing after some long tough game session (then again just playing the game itself can be quite rewarding, so you don't always need a reward anyway). Just don't relay on the fact that everybody considers an epic cinematic a reward.