In the past it would be pretty much impossible to download apps over mobile networks, simply because platforms such as iOS and Android would not allow it, or when they did the limit would be so small that bigger apps are pretty much a no-go. These days the limits have increased, although Apple and Google do still warn users against using mobile data for downloads.
However the good news for Android users is that Google could be introducing a new feature in the future in the form of queuing up app downloads. As you can see in the screenshot above, when not connected to WiFi, users will have the option of queuing up the download so that when they get home and are connected to WiFi, the download will begin.
This will be pretty handy for those times when you are out and your friend suggests an app to download, only for you to forget about it when you get back home. With this new feature, you just need to fire up the Play Store, queue the app, and you’ll be set. That being said, as you can see in the screenshots it is clearly labelled that this is a beta feature.
What this means is that Google may or may not proceed to make it an actual feature, or what you see now could change upon its release, although admittedly in its current form it does seem to be pretty good.