Money, Mark & Joy of Bible study: some exegesis

In our study of the Gospel of Mark,  Long said something that seemed really insightful  about the beginning of Mark.  We looked at Mark 1:

⁴ John the baptizer appeared in the wilderness, proclaiming a baptism of repentance for the forgiveness of sins. ⁵ And people from the whole Judean countryside and all the people of Jerusalem were going out to him, and were baptized by him in the river Jordan, confessing their sins.

When we asked the question about why people were so receptive to the message of confession and repentance, Long wondered if perhaps the people from the Judean countryside were poor people shut out from the temple (which we learn was oppressing the poor in Mark 11). In this reading, the appeal of John's baptism of repentance might be a deep resonance with people who experienced first hand the exclusions and hypocrisy of the religious institution.  If so, it would anchor themes of money and justice in the very beginning of the Gospel.  John's message preparing the way of the Lord is one of justice. 
 
And what of Jerusalem coming out?  The phrase might only indicate everybody came out, hillbillies and sophisticates, but it might be a wink that the temple had failed even the religious.  Or it's just geography.  Still, with Mark's economy of words, I suspect there may be more here. Has this reading been entertained or explored elsewhere?   I would love to hear your thoughts or find resources addressing this issue if they exist.  I have never considered this before.  Praise God for studying the Bible in community.