Many producers see that demand for Lite versions of applications is very high, and they usually release two variants of app: standard, dedicated mainly for better phones, and lite option for users which don't want to spend a lot of money on the phone or for those who just want to use main functions of apps. Most of the biggest apps like Facebook, Twitter or Skype have Lite version of their main app, and this trend probably will continue, and that's why Google modified a bit their Google Play Store.
Change is dedicated for people with weaker smartphones, because under standard version of apps Google Play Store will show us announcement that this app has Lite or Go version, and on the bottom we will have direct link to this version. This feature will slowly come to all countries all around the world.