Well, like hangman, I would question whether humanity needs religion at all, never mind does it need leaders ;)
That having been said, all organisations require guidance/leadership - Thats the way we are - a figurehead to articulate the views, so while we have organised religion, we will continue to have religious leaders.
How much influence should they wield in secular and political matters though is a good question though. The bishops should not be given an automatic voting block in the House of Lords. It is desirable and necessary for there to be a clear separation between the church and the state.
And whilst they might have time for reflection and thought, as OG suggests, that reflection and thought is coloured by, biased by their innate religiosity which increasingly leads them into conflict with the secular majority, especially when it comes to equality, the role of women, and sexuality.
Hence the shambles that religion finds itself in within the UK with respect to Women Bishops, or gay marriage, or abortion. Marriage is defined by culture, but at its heart it is a secular issue - of rights responsibilities and obligations between 2 people and their estate; an institution which acknowledges interpersonal intimate and sexual relationships. The culture defines it, the state validates and legislates for it, and the churches have traditionally been the focus for the celebration of the union. But the culture determines what marriage is, not the churches, just as the culture determines what is and is not socially acceptable in matters sexual, not the church, and its about time that organised religion recognised this.
And when you get leaders you will get corruption, because ultimately power grants privilege and patronage, and privilege and patronage can lead to corruption. Hence we see a parade of church leaders who do nothing but bring their church into disrepute and increasing irrelavance;
Heres a small selection for you;
http://www.nytimes.com/2012/04/06/world/europe/in-russia-a-watch-vanishes-up-orthodox-leaders-sleeve.html?hp&_r=0
and then this lot of evangeiical christians
http://en.wikipedia.org/wiki/List_of_scandals_involving_evangelical_Christians
And the list goes on - latest signatory to the list? The Indian Swami who claimed the woman raped in the bus in Delhi was at fault, was culpable for her own rape as her attackers.
So, being a religious leader quite obviously does not automatically confer wisdom, or humility, or progressive values.