But some have enough memory that you would probably not miss the SO-DIMMs, I mean, do you have a workload needing more than 32GB that you would run in the notebook (with the limited CPU and thermal constraints)?

But just 8GB in a non-upgradeable package is not for me.

The new T series models all have soldered RAM AFAIK. Lenovo seems to be putting SO-DIMMs only on select P series (i.e., actual mobile workstations, not T series branded as P).