If one wants to stand, more power to them.  For some of us, standing is difficult and a chore.  
I don't think that there is any one posture that, by itself, improves participation in Liturgy.  I have seen many people who are standing, but from their facial expressions, it is clear that their thoughts are not in the present.  But you are certainly free to disagree with me.
Re the various postures during Liturgy -- in some Eastern Catholic Churches, people do not kneel at all (eg http://www.epiphanybyzantinecatholic.org/faq.html).  There are still many, throughout the world, where people stand for the entire Liturgy.  I don't know enough about the history of the Mass to know when and how the various postures developed.  
I always become wary when it seems that people start romanticizing anything -- in this case standing.  I know from personal experience and observation that standing during the entire Liturgy can be difficult for many and does not guarantee engagement.