Quote - The "single good reason" I can think of is that I open a zip file and drag the Runtime folder wherever, and it merges everything automatically.

Otherwise I'd have to drag Geometries, Textures, and Libraries, and sometimes Python - four drags instead of one.

Or, if the zip file had a top-level folder with some arbitrary name, like V4CoolStuff, and I wanted to install it in my V4 external runtime called V4 Runtime, I'd have to drag V4CoolStuff to some temporary place, change the name to V4 Runtime, and then drag it onto my existing V4 Runtime.

Either way, it's extra work. I know people say you shouldn't just drag a zip contents somewhere without examining it, but I have no trouble examining it while it is still in the zip. Then I drag it.

My main runtime is the product of six or seven years of accumulating stuff.  It would be entirely unmanageable if I let merchants choose how their geometries and textures and poses and lights and such get embedded in my runtime... so I always drag stuff where I want it and relink.  It is more work, but I can keep all textures and geometries and poses and such organized in "file cabinets" through an intervening directory level (e.g., textureseye textures...etc).  This approach includes using a "to be tested" cabinet where products can be tested before being promoted to my main runtime.  But again, I know my situation is probably unique, especially since these habits and workflows were formed way back when you could only have a single runtime (having started with Poser 4).  In any case, I like to keep as tidy and lean a runtime as possible, dumping unused geometries and textures and such to external holding bins.  This approach would itself be unworkable if not for CRPro, which not everyone has. 

But that leads to a thought... maybe P9 could have a CRPro type utility built-in to help people manage their inevitably bloating runtimes.