It isn't sloth that causes films such as this, it's cowardice. It's far easier to get money for a movie where you can point at something very, very similar that happened to make money. This is why remakes happen: You can say "look, but it made money the first time, unless we really fuck it up it'll make money this time." What's diminished are standards. The remake if Clash of the Titans did a lot worse than the original Clash of the Titans and the orignal Clash of the Titans was considered enough of a failure that nobody bothered with a sequel. The remake? Yeah, its sequel was greenlit a week after open.
Clash of the Titans (2010):
http://www.youtube.com/watch?v=FXttqg0RWU8 Wrath of the Titans (2012):
http://www.youtube.com/watch?v=Xs7fzOrUopc Clash of the Titans, 1981, did $41m business on $15m budget. It didn't quite scrape the top 10 for 1981. Granted, it's a hell of a list - but the '81 version was beaten out by fucking Time Bandits. Clash of the Titans, 2010, did $163m domestic on a $125m budget. It did triple that foreign, which makes it about doubly successful as Eragon, widely regarded as a total stinker. It's $300m short of Lion, Witch & Wardrobe (which, admittedly, cost a lot more). It came in at #14, behind True Grit and barely ahead of The King's Speech. But it got a sequel.