Everybody copies everybody else I guess.
But Why does Marvel Comics allow it?
It can be clearly seen that "The Incredibles" is a copy of the "Fantastic Four"
They are not an exact copy, but close enough.
"The Fantastic Four was the first superhero team created by writer-editor Stan Lee and artist and co-plotter Jack Kirby"
"The Incredibles is essentially an animated version of Spy Kids. Or maybe Spy Kids meets The Fantastic Four. Actually, so much is borrowed from The Fantastic Four, I wonder if those not in the know, will think The Fantastic Four feature film, due out next year, is stealing from this. Hopefully there will be room for both. Ironically, I can't even begin to imagine The Fantastic Four being as action-packed and full of as much fun as The Incredibles. Despite its heart being two sizes too small, The Incredibles is a wild ride worth taking again and again."
"The Incredibles parodies or draws inspiration from a number ofdifferent comics. It most heavily resembles the Fantastic Four. Theyreiterate a lot of the family themes of that comic and, more notably,the superpowers. Elastigirl is like Mr. Fantastic, Violet is like TheInvisible Woman, and Mr. Incredible is like The Thing. I guess theydidn't want kids imitating The Human Torch and setting themselves onfire, so Dash has super-speed like The Flash instead. (All this makesme wonder if audiences are going to think that the Fantastic Four moviecopies The Incredibles rather than the other way around.) MeanwhileFrozone imitates Iceman from the X-Men comics to a greater degree thaneven the X-Men movie did. The film really copies a lot of the tricksthe heroes do in the comics. For example, when a plane blows upElastigirl copies Mr. Fantastic and makes herself into a parachute.Dash is able to run on water like The Flash. While it's not terriblyoriginal to copy the tricks from the comics, it's still very cool tosee it played out on the screen. Audiences that aren't cultured fromreading comics will be very impressed."