Nowadays, a phone is not just a mere object used just for conversations, it is used for many other things (Example, searching the web, playing games, setting notes, reminders, watching high quality videos etc) out of which many require a stable internet connection either through mobile data or through WiFi. People usually prefer using a WiFi connection rather than using mobile data mainly because of low battery consumption, and a more stable connection.
Users rely on a sturdy WiFi connection for doing a multitude of things on their mobile devices. You most probably have a few WiFi networks saved in your phone for the various places you go,like one for the office, one for your home, one when you visit your friends house (Like me). People usually take it for granted that their phones will get connected automatically to their saved networks when they come within their ranges. But recently, many people have been complaining that this feature has not been working properly since upgrading to Android 4.3.
The common complaint among most of the users is that when one takes the phone beyond the range of a WiFi network for more than a few minutes, then the phone is unable to reconnect automatically to the network when a signal is found later. Most of the times, this can be fixed by toggling the WiFi (i.e. turning it OFF and then back ON again) or even by doing a manual scan again. This problem has been faced generally by the Galaxy Nexus users and also some users of the Nexus 4.
Although this might be a only a minor inconvenience for some and could be ignored, for others, it could be a quite an annoyance as this could lead to substantially higher data usage on ones cellular connection. Also, battery backup would be another problem that the users will have to deal with as using the cellular data connection tends to drain more battery than a WiFi connection especially for Galaxy Nexus users.
Despite the growing number of grievances (AOSP Issue Tracker #58230), the Android team has still not officially acknowledged the bug. If you have experienced similar problems, raise attention by sharing the issue. You can also leave a comment if you have got anything useful to add. Till a true fix has been found, one can temporarily fix the problem by setting up a Tasker profile which resets the your WiFi regularly whenever it is turned on but not already connected. For a tutorial for the fix, check out the post by stevensoaj on XDA Developers.