The company's statement says, " When we started WhatsApp in 2009, people's use of mobile devices looked very different from today. The Apple App Store was only a few months old. About 70 percent of smartphones sold at the time had operating systems offered by BlackBerry and Nokia. Mobile operating systems offered by Google, Apple and Microsoft – which account for 99.5 percent of sales today – were on less than 25 percent of mobile devices sold at the time".
So in order to maximise profit and protect the app which is now used for business all over the world and tears directly into peoples privacy due to synchronization they wish to give better protection - its all about better service.
"This was a tough decision for us to make, but the right one in order to give people better ways to keep in touch with friends, family, and loved ones using WhatsApp. If you use one of these affected mobile devices, we recommend upgrading to a newer Android, iPhone, or Windows Phone before the end of 2016 to continue using WhatsApp."
"As we look ahead to our next seven years, we want to focus our efforts on the mobile platforms the vast majority of people use. So, by the end of 2016, we will be ending support for WhatsApp Messenger on the following mobile platforms"