> the need for having a permissible license for the dual-license.
A more permissive license generally improves adoption. For the same level of adoption, a less permissive license drives more revenue in the dual-license model. Maybe a permissive license is still the way to go (certainly getting adoption is often difficult), but it is not the dual license situation motivating that. Contrast a "give away the software and sell support" business model, where (sufficient) adoption is everything and more restrictions on the license doesn't do anything for the business.
With a maximally permissive license, I hesitate to call it "dual licensing", as it stops being the license your paying customers are actually paying for but rather hosting, support, or warm fuzzies.
> a less permissive license drives more revenue in the dual-license model.
But we've so far encountered just one example for that, Even there we don't know the financial status to claim whether it's indeed more successful (revenue wise when compared to a permissible license).
On the other hand we have numerous successful products (by revenue) with permissible licenses incl. those sighted in the OP.
A more permissive license generally improves adoption. For the same level of adoption, a less permissive license drives more revenue in the dual-license model. Maybe a permissive license is still the way to go (certainly getting adoption is often difficult), but it is not the dual license situation motivating that. Contrast a "give away the software and sell support" business model, where (sufficient) adoption is everything and more restrictions on the license doesn't do anything for the business.
With a maximally permissive license, I hesitate to call it "dual licensing", as it stops being the license your paying customers are actually paying for but rather hosting, support, or warm fuzzies.