CodeIgniter is one of the world’s most popular Open Source PHP frameworks, used by thousands of developers powering hundreds of thousands of sites, in addition to being deployed as the underpinning of every ExpressionEngine installation. Throughout its seven year life thus far, CodeIgniter has consistently received praise for being both speedy and surefooted. Small and lightweight, resistant to feature bloat, retaining compatibility with contemporary technology, the framework earned the reputation of being low-risk and high-gain, which fueled its worldwide adoption. So why are we we looking for a new home for CodeIgniter?
They go on, talking about their reasoning behind moving on from CodeIgniter - mostly it's concerning the resources they have available and the things they, as a company, want to focus on:
CodeIgniter will be best served by someone with a focused vision for it, along with the resources to achieve that vision. It needs someone to skillfully utilize the brand’s immense traffic, and direct the thousands of voices of input towards common goals. EllisLab can’t provide those things without adopting a fundamentally different business model or taking attention away from our primary flywheel. CodeIgniter deserves to be someone’s primary flywheel.