One of the popular reasons why people jailbreak their iOS device (and not update iOS version) has unexpectedly shut down just recently.
Hackulous is a development team and a Cydia respository which hosts the infamous Installous, an app that allows you to install cracked version of iOS games on your device bypassing the App Store.
Visiting their website will show you a short message from the team.
We are very sad to announce that Hackulous is shutting down. After many years, our community has become stagnant and our forums are a bit of a ghost town. It has become difficult to keep them online and well-moderated, despite the devotion of our staff. We’re incredibly thankful for the support we’ve had over the years and hope that new, greater communities blossom out of our absence.
So it’s not that they were forced to shut down. I’m guessing this is mainly because of long wait times for the jailbreak to catch up to the latest iOS. Current untethered jailbreak is still at iOS 5 and there’s no available jailbreak in sight for the latest iOS devices including the iPad mini and iPhone 5.