The problem is your then left trying to figure out which blobby blob of astral matter is the one you want to communicate with and whether you can astrally manifest if there's no one there to see you.
You see as if you were on the astral. So you can still see auras and the general shape and appearance of people, both of which are easy to use to identify someone. Unless you're expecting to make liberal use of Astral Projection and refuse to put points into Assensing, that's not really a problem. And sure, you can manifest when nobody can see you. As devices can't record you, I cannot think of a single situation where you would
need to manifest, but there was nobody around, and that mattered.
My personal workaround has always been to houserule it a little so if you manifest your moving your mind from astral perception to normal perception i.e. no interaction/technology recording/etc as per the rules there but you can see the real world now instead of the astral one. Of course the drawback of this houserule is that since you aren't astrally perceiving when "manifested" you wont see anything on the astral for that period. I don't think it conflicts with the intent of the rules and it allows me to feel a little more comfortable with how it works.
If you moved your perception back to your
normal perception, you would be seeing out of the eyes attached to your
real body, which would be still unconscious with its eyes closed (probably). As I said, your physical senses are part of your body. Astral Projection is leaving your body behind, thus leaving your physical senses behind. If you want to see an area from far away using magic, as it exists in the real world, use the Clairvoyance spell. Astral Projection is very powerful as is, it really doesn't need a houserule to make it better.