What's quite interesting is that a few years ago, when you bought from the MAS, you assumed you will always be able to install the software and it will be kept

What's quite interesting is that a few years ago, when you bought from the MAS, you assumed you will always be able to install the software and it will be kept up to date. Nowadays, the unfortunately reality is the opposite - it's very likely the MAS version is seriously lagging behind. What's worse, as you say, is that there's absolutely no indication that some of those apps have been abandoned (apart from the very old Last Update date). The vast majority of consumers will just buy the software and not go researching whether the app they're acquiring has been left collecting dust. And at the end, both consumers and developers lose out.