Don't get me wrong, I wasn't having a go at Canon (I have used Canon my whole life, starting off with film and moving through the 350D, 60D, 5D3), however how many of the updates you mentioned were done after the release of the 7D2? My point was why would Sony update the AF performance of the A7 when tit has been superseded by the A7ii and soon to be A7iii.
Have a go at whoever you want.

Canon didn't have to release a firmware update for the 7D, it was presumably selling well against the even then ageing Nikon D300S. Now maybe, the update would have given them a sales boost though, and maybe bought them a bit longer time to prepare the 7DII. If companies continue to support the cameras with improvements via firmware updates that would be great, but you can see it is not in their best interests most of the time. It could foster more loyalty from user because they would feel that the company 'cares', but improve too much and users are less likely to upgrade when the new camera is not that big an improvement. It is a tough road to thread. Maybe it is easier to do in an expanding market, which the mirrorless sector is, because more people will probably buy any new camera regardless of the few that will stay with their firmware improved cameras.
The only thing that puzzles me about Sony, is why do they continue to build and sell older models after releasing updates versions for example A7/A7ii, RX100 1/2/3/4 etc
Normally what happens is older cameras stay on sale because stock has not shifted off the shelves, and they want to bring out a new model. It is normally in the entry to mid level cameras because they are normally released every 1-1.5 years. They have over produced and they haven't sold enough to get close to clearing the stock out there. I noticed it first with Canon, who would release a ***D camera and there may be one or two previous models, at time reduced rrp, for a number of months. It was easier to do when there were larger improvements for each new generation. There was a time a few years ago when Nikon had 3-4 generations of entry level camera on sale.

We are getting to a point now where a new camera may have some minor improvements but maybe some features of a previous model taken away.

Seriously Nikon, taking away sensor cleaning from a DSLR.

Presumably for cost cutting reasons, but it seems a stupid business model to me when there are plenty of the previous model, and maybe even the one before, still on sale.
Sony seem to be trying something different with the RX100 series at least, in making large improvements to each model, to raise the price of the new camera, and so have many of the models still on sale appealing to different users in features and price. For me, the RX100 was the best combination of features and price I wanted to play for that type of camera. For that to work they seem to be keeping the prices relatively stable, and prices not coming down over time as quick as most cameras.