Problem is the 380s are based on the 332, not the 350. The 350 design is essentially scuppered because of the front gangway. Remember that the 350s only exist because DfT or whoever they were back then didn't want 30 extra 450s going to SWT, and so they were re-allocated to CT/Silverlink. Hence the 350/1s have a third rail shoe. The new 350/2s arriving later this year are the same design, but with no third rail capability and 3 by 2 seating throughout Standard.
Also, the 360s now on the GEML were originally meant to have a gangway, and the pre-prod models show this gangway. However, the HSE wasn't happy with the forward visibility and so it was discarded.
My guess is the new front design is to allow for maximum forward visibility so that HSE don't get a rat up their arse.