Phone Arena posted an interesting question on its site. Should Google remove the option to sideload Android apps? The main reason is it makes app piracy a bit too easy. "The solution to all this seems quite simple to us - get rid of the option that allows you to install apps from sources other than the Google Play store."
I think the answer to that question is an easy yes. Most users do not need this feature. Leaving it poses a security risk. The only app I have ever sideloaded what Gameloft's GTA Racing Motor Academy, which I bought when it was not yet for sale in the Play Store. By removing side loading, the Gameloft will simply be forced to sell their all Android games through Google Play. Actually, I be mush happier if this was the case.
The objections are that removing the sideloading option is not needed. Apps can have an authentication system. If this is the what developers have to do, you will get all sorts of complaints as to why the app has to connect to the internet. Developer would have to spend more resources maintain servers to authenticate their apps.
Others, object on the grounds of freedom and openness. If you want freedom, root your phone.
Yes, you will be closing the marker to a degree. But, it is not like Google Play is vetted or restricted like Apple's App Store. Removing the option to sideload apps will not close the ecosystem.
I really cannot thing of a good reason why this feature is useful to the average Android phone user. Well, that is my 2-cents.