I know the new Local V5 is much faster to boot up and start your project. But at what cost? Everything now is running on your local machine instead of a virtual machine. That means if you need to do some custom development and need to install some additional thing to the server, you need to install it on your actual system instead of a virtual machine…
Alongside, you also need to do custom, complicated configs on your system in case you need different configs for different projects.
Another reason is that a lot of developers use Local for other than WordPress development. I know this is not officially supported and this is not what Local is built for initially but perhaps others will agree that they would also like to have an option to at least switch between local development and the old VirtualBox way so they could customize the system the way they need for the project on a virtual machine.
I believe you could just stick with the V3 but since it won’t ever get updated, you won’t be able to switch to a newer version of PHP or MySQL as easy as you would have before.
Hope this request will get some attention!