A Mac Pro is not 'portable' if you still have to lug a screen around.
Yes, and? The same argument applies for a "laptop" that you MUST lug a power adaptor around with constantly. That is not a device amenable to using on the patio or the bed. In fact the choice Apple made seems like the are tailor made to the case you lay out - which how most people (including myself) use laptops, and why suffering a huge hit in battery life just to go beyond 16GB is a non-starter.
I absolutely need 32GB in order to be properly productive.
I find this very dubious considering much of the work I do is very memory intensive - iOS development and a lot of high-resolution photography including some huge panoramic work, more recently some neural networking stuff - would I *like* more memory? Yes. Do I *absolutley need* more memory? No, I get by OK wth what I have now. If anything the real memory need people would have for modern tasks is not main system memory but GPU memory, and there Apple is still doing OK with 4GB of memory, if anything else I would have liked to see more there.
Most modern professional apps are used to dealing with partitioning tasks into smaller amounts of memory and the main SSD on the new MacBook Pros is extremely fast, making those applications run quite well (mainly affects the pano work I do).
If you look at Activity Monitor sometime, I think you'll be surprised at how much memory you actually use...