I want the ability to tell Protools where to go look for my AAX plugins (or any other plugins). Currently, you have to store all plugins on the C: drive. I use the C: drive of a Windows box for my operating system only. I have a D: drive for all my applications, sound files and plugins, and I have an E: drive for my Protools project files and song ideas. The C drive is a standard mechanical drive, and the D & E drives are solid state for faster access times - by design, for programs that draw a lot of samples from the app drive. I don't want BFD3 or other heavily sample based app hitting my C drive and clobbering my operating system when it soaks the seek time.
I would like the ability to tell Protools which drive to install on, and on which drive the plugins should reside. At minimum, I would accept PT making me install on the system drive if that was my only option, but I definitely want the ability to store all my plugins on another drive, and to be able to tell PT what the path is to my AAX or other plugins.