He's with us always, but why can't we have Jesus in the Monstrance 24*7?
It is possible and some parishes do. However, the Church requires that if the Blessed Sacrament is exposed that someone be present with it for safety sake. Otherwise someone could vandalize or desecrate the host. In many places it is not possible to arrange for people to be present with the host 24/7 and thus they do not have 24/7 exposition.