I thought G.I. Bunker was the guy on "Ghostly Images" from the Realm of Discord, but that's not him on there. That Bunker and the be-goggled Legacy fighting next to him look like they're probably one revision earlier than WWII, I'd guess, so WWI-era.
For both the WWII and WWI versions of Bunker, one thing stands out to me in the design of their suits - it must be irritating to not be able to move your head because it's attached by a hose to your chest...
It was also irritating not to have air conditioning - those suits can get hot!
There have certainly been a number of technological advancements to the Bunker since the mid 20th century, a fact for which Tyler Vance is most likely quite grateful :)
I don't have the cards with me, but can we see the G.I. Suit next to the Ghostly Images on the decommissioned hardware art? I think I remember 3 suits on there. The one with tank treads is pretty weird. Maybe it'll debute in Sentinels Tactics!
Even without the tube, I think GI Bunker would have a hard time looking around. As the glass on his chest is where I think his head is and is where he sees out of. As for the Bunker suit on Ghostly Images, he may be in a position to where he sees through the head or the tube on that one works something like a periscope, allowing him to see through the eyes of the suit.
Edit: Infact you can see the GI Bunker suit, it's the one on the right.