Because Sony Xperia L has not been receiving quality software upgrades from Sony , sometimes which have software issues. Also a lower device Xperia M has surpassed it in Android version. And Xperia L now runs an obsolete version of Android. And its now very late to update to Android 4.3.

Letter to
Sony Mobile Communications Sony Mobile Communications
Kindly update Sony Xperia L to Android 4.4 (KitKat) as soon as possible , because it has not received Android 4.3 which rest of Xperia phones received , and also now its very late to provide Android 4.3 update so please carry forward this request and update the Sony Xperia L to Android 4.4 , and please be quick enough as it is fast approaching its 18 month update period's end. Even if update period ends at least update the device to Android 4.4

Thank You