Thanks for taking the time to write this, you do make some good points! And the 'mouse utopia' experiment was very interesting, I hadn't seen it before and it's similarities with human-society are quite striking.
You did give me some things to think about, I agree that a malnourished social life will most likely have a huge impact on our spirit, but I'm not convinced it is the biggest factor. At least, not in my case. To give you an idea of my situation, I'm a highly sensitive (en.wikipedia.org/wiki/Sensory_processing_sensitivity) and introvert person, whose chains of extreme social anxiety have loosened only within the last couple of years. As of now, I have little problem interacting with others, but I also have little need for it. In fact, I cannot get sufficient mental rest if I don't spend the vast majority of my time alone.
I think the biggest impact generally comes from the nature of activities and the mindset wherewith we partake in them. The Spirit of the Lord is grieved by sin, and will obviously not be with the people who live in it. If we partake in activities that glorify sin (certain games, music, movies, series, etc), and if we delight in them, then we are glorifying those sins as well. I'm convinced that this has a similar impact as committing the sins themselves.
The carnal mindset has this impact as well, though I believe it to be more subtle. The carnal mind is enmity against God (Romans 8:7), so it's obvious that God's Spirit doesn't abide in those who have a carnal mindset. As you most likely know, carnality means 'worldly'. The 'carnal mind' refers to those who live worldly, to those who live for themselves instead of for God.
I think the biggest reason for the fact that so many "Christians" aren't experiencing (much of) God's presence, is that, while most of them try to get rid of all (well-defined) sin from their lives, they forget that they are no longer their own (1 Corinthians 6:19-20). They still (to a certain extend) live for themselves and want to stay in control of their lives. The only way to get close to God, is to surrender your life completely to Him. This is what it means to forsake everything you have (Luke 14:33), to trust God for everything you need (Matthew 6:24-33), and to acknowledge Him in all your ways (Proverbs 3:5-6).
To get back to my own case of feeling spiritually impaired after certain activities.. Spending hours, playing games, watching series, expanding my movie or music collection… that was me "living for myself". Those things were my treasures, which means that (in those moments) my heart was in them, and not in the Lord. This is in stark contrast with the days I largely spend reading and studying the Bible. In those days I feel more satisfied, at peace, and spiritually alive than ever.
Of course, things like playing a game, watching a show, or listening to music are not inherently evil and we don't have to give them up (unless they glorify sin), but if those things are our treasure, then our heart is not with the Lord, and His Spirit will not be with us, rendering us spiritually impaired or dead.
I guess I'm repaying your wall of text with another one.. but I thought this would be useful as well.