The days of Google encouraging third-party stores and users to sideload apps regardless of origin are long gone. We are fast approaching Play becoming as near a simile to Apple’s App Store as we could ever see.
I think it's a stretch to say that Google ever encouraged side loading. But if their plan is to eliminate it all together, that's a pretty scary thing. I don't think it'll go over well in Europe either.
There are lots of features that used to be common that just didn't make the cut for one reason or another. I still have old phones with a radio tuner and programmable IR remote. Some features just took up too much space, some complicated the manufacturing process.
Some of them still have enough of a market to justify for some manufacturers.