This is difficult for me to answer, yet stay within the post guidelines as it states that we are to answer the question, yet avoid making statements based on opinion.
I agree that it is very inconvenient as well for larger applications such as Visual Studio as you said, but the others are programs that I use all the time and would like to be installed on my OS drive (I am assuming you are referring to smaller, faster drive for speed sake.
As a hunch, it could be something to do with companies moving to a more "It just works" type set-up, or tailoring their installs to be as simple as possible to be as little daunting as possible as well. This would make sense for things like Chrome or Office which are typical applications that many home computer users would use, and care little about their location.
On the other hand, I'm countering my own argument with applications like Visual Studio and SQL server, as these are typically applications that involve the user "getting their hands dirty", rooting around in code and making things work how they want it to.
In summary, it is difficult to answer this question without an opinion, and my opinion is that developers think they know your computer better than you do.