hmmmmmmmmmm....he's not only a religious leader, but also a head of state (the Vatican) ...few other religious leaders (that I know of, pardon the ignorance) are also heads of state...partly, also, because of the importance that the Catholic church had traditionally as a political force (I remember from school that the first son from the "noble" families always stood to inherit, while the second one always had to go into priesthood, to consolidate the family's power)...and, I imagine, too, partly because Catholicism is the "root" religion for most other Christian churches...
That is what I can think of as for the respect generally given to popes...as far as JPII goes, he, as I said before, was a true Leader (capitalized on purpose!)...the man had charisma ...he reached for the people, and the people (of whatever denomination) responded...especially the younger generations, who, in todays world, seem often to be "disconnected" from the church ...If you had seen the reaction whenever he addressed youths, you'd have thought he was a rock star or something...He came twice to El Salvador, and, when he arrived at the Cathedral for the "Meeting with the Youth", the chanting of Juan Pablo II, te quiere todo el mundo" was deafening...He also seemed to thrive in their presence, to become younger...I particularly remember his second visit (1996), if only because I was older!...he was looking tired but, right in front of our eyes, he became renewed by his contact with all these youngsters...and, as we can see from other posts linking to various sources of information, he did A LOT for the Catholic church and for "opening" it to other religions, as well...