Many traditional meditation techniques recommend closing the eyes. For the reason that visual stimulation takes up >75% of our perception.
Closing the eyes automatically makes it harder for our mind to wander off. Still hard enough, but at least you won't be distracted by those nice lights on the wall (or similar).
I have read some zen meditation material and I remember them usually suggesting to meditate with your eyes open, but not all the way open. If you are in the traditional mediation position, looking a few feet ahead, towards the ground with eyes about 25% open. However, being new to this and trying to learn, I have had better results with my eyes closed.
Yes, zen meditation is with the eyes partially open. About 25% like you said, but it should just be this natural state that the eyes get when you relax and star at the blank wall.
There are many traditions that also have an eyes-open approach. I'm constantly amazed by this propagation in the West of the idea that meditation has anything to do with the mind 'wandering off' (or not wandering off, e.g. extreme concentration or 'awareness' as is the current buzzword).
This is unfortunate because it tends to make practice feel difficult, as our minds naturally wander, and then come back, etc. People connect their perceived success at this with their experience of practice, and quit or go off on very strange and contrived tangents. The notion of success/failure is typically irrelevant in many traditional meditation practices.
I always started by closing my eyes, but found that having them open felt... better. More natural. Not exactly sure - i just started preferring it. FWIW, there are some popular books[1] that recommend the eyes open approach - which surprised me when I first read about it.
I agree wholeheartedly with the rest of your post.