We’ve already done that for one of our product, I am unsure of all the motivations (this was made before I came, by the guy I am replacing)
What I have found so far is that this product (AnalogFactory) is a kind of integrator for other plugins we made.
One of those plugins (Jupiter-8V) is also built with Juce, but based upon a different version.
Communication goes beyond VST integration, and some source files have access to GUI classes from both products, and so the integrator product is compiled using another namespace for Juce to avoid a complete mess.
This probably could (should) be solved another way, but I don’t really have the time right now to change that.
I am in the process of updating Analog Factory, and to be able to use the new plugin hosting classes, I am upgrading from Juce version (holding breath) 1.30 to version 1.46.
Actual conversion was made rather easily on the Windows platform. On the other hand deploying the changes to Mac OSX is kind of a nightmare…