Diablo 4 does not allow inventory expanding but Blizzard is working on a change
gamerkick.com
Blizzard admits to being aware of requests from the Diablo IV community regarding inventory expansion, though it doesn’t look like the feature is coming anytime soon.
I always liked how they solved this annoyance in Torchlight, where you could load up your pet with loot and order it back to town to sell/salvage everything.
Swtor had something similar, companion would take 3 minutes to run back and cash out junk for cash, you felt it but it wasn't crippling.
It's so annoying how they're dragging their feet on this. What is the point of having such limited inventory slots when TP's are free? It only serves to waste people's time, forcing them to go back to town multiple times mid-dungeon. Just give us more stash tabs and inventory slots already and let us loot in peace.
Pretty sure AI wrote this article
Certainly going to be a paid "feature" as well.
This is exactly my thoughts and it's "by design." I totally expect them sell stash stabs like POE.