Why does God not bestow the gift of Holy Spirit power on any and everyone?
Why did God cut of access to the Tree of Life when Adam and Eve sinned?
I think the answers are embedded in the last question. The way our minds work is by punishment and reward, at least after sin twisted them. In fact, that principle itself might possibly be a legacy of the Tree of Knowledge of Good and Evil. Because we ate and continue to eat from that tree and operate under its influence, God has to reach us in that state of mind. We believe that religion can only be successful if we use a mix of love and fear (good and evil). It seems ludicrous to think we could ever operate in a system of only good, positive, thriving, compassionate etc. environment completely devoid of all fear motivation. And yet this is precisely why God refused to stop the sin experiment of Satan; because He wants everyone to be completely free of all fear in their motives for serving and loving Him. If that's what He insists for the universe, why do we think it won't work here?
If God were to give us the things in the first questions above without any conditions, the way our mind operates would cause us to believe that our current beliefs (misconceptions about Him) are justified and we become more deeply entrenched in our lies about God. This is the underlying root that blocks God from giving us certain privileges. In effect, they would lead to immortalizing the very lies about Him in our minds that keep us away from Him to begin with. We cannot be given access to the immortality inherent in the Tree of Life until we have released and renounced our false ideas about who God is and what He is like. We can't receive infilling of the third person of the God-head while we believe and promote lies about that same God.
God's promises are not yea and nay but YES in the Holy Spirit. (2 Cor. 1:19,20)
There is no fear in love, for fear involves foreboding in anticipation of punishment (1 Jn 4:18)