I've always used a full cage, and have never had any vision problems. I don't even notice the bars, which are black. I've even started wearing my glasses to play because I hated wearing contact lenses to play (and haven't done so in years), and the only vision problem I face is that of my glasses fogging up.
Back in the 1970s hockey, broomball, etc. players had cats eyed cages without chin cups.
On a team I played on 5 years ago the oldest player wore a cage like that, his helmet was made by Spalding and had the 'hat size' printed on the back. Only photo of him I have is a team photo with his helmet in his hand. He is in the front row with the 'A'.
I got hit square in the face/cage with a puck a few nights ago by a very hard slap shot taken about 15 feet away. It pushed the chin cup into my chin so hard that it dazed me and my jaw hurt for a good 5 minutes afterwards. I would have hated for that to have been the metal of the cage hitting me rather than the chin cup.
The acceleration of any high energy impact will be compounded with any significant gap between the sending force and receiving object. Another thing that absorbs impacts are actually the J-clips. If your cage is large enough that it will hang naturally, any impact will have the cage hit the clips first before your chin.
I have some hang to my cage too, it's purely a comfort thing.
I'm not telling anyone to do anything, I'm arguing that it is safer to not have hang. Whether or not a person does is purely their own decision and all fine as long as they know the risk. It doesn't hurt other people.
As someone selling cages and helmets among other things, I will never advise anyone to have hang, as part of my responsibility and liability to an extent.