Sections left over from taking a wall out - can you get rid of them?

[NineNine]

See photo

I assume it’s done like that for structural support. How big a deal would it be to remove them?

I never manage to keep a straight face when referring to full penetration butt welds if you want more amusing engineering terminology! Shaft friction and ring shear tests also get sniggers...

DH is FIStructE and we don’t have nibs in any of our opened up spaces. Nor do we have portal frames everywhere. We have load bearing walls.

The requirement for nibs and/or other lateral support to walls depends very much on the condition and construction of the original house. If yours has sufficient thickness in the walls to allow these to be dispensed with, that's great. But where nibs have been left, it's generally for a good reason and therefore lateral support should continue to be provided.