You’re right. Today we rarely see people kneeling in our churches, except in more formal, liturgical services (many of which, by the way, offer kneeling benches in the church for that). I think that when we pray on our knees it is a physical reminder of our submission to God and His working in our lives. He’s our Creator. He is our Lord.
Of course, He is still Lord even if we stand or sit before Him to pray. It’s not about our physical position. When the priests in the Old Testament ministered in the tabernacle before God, they normally stood. In Ephesians 3:14, Paul says, “For this reason I kneel before the Father.” When Solomon dedicated his temple to God, he knelt as well. David said in 2 Samuel 7:18 that he went in and “sat before the Lord” to offer thanks to his heavenly Father. So prayer is acceptable to God no matter what our posture is.
As for praying with our eyes closed, personally I find myself less distracted with my eyes shut. I had a friend who in the early days of contact lenses, found it difficult to pray with his eyes closed. And frankly, I don’t know of any Scripture that demands it. In most cultures praying with eyes closed is a learned behavior. It’s the way we see other people pray. When I’m driving, I can still pray even though I’m watching the road. I have a wonderful conversation with God with my eyes open—it’s a true blessing. I spend a lot of time on the road commuting to work, enjoying prayer times with God, even with my eyes wide open.