Why is there so much secrecy between greek organizations?

[g41965]

Delta Upsilon is non secret. Initiation is open to members and invited guests alike. Due to my involvement in DU I became interested in the secret/nonsecret debate, this is my take on the issue.
Most fraternal organizations derive ritual from the masons, odd fellows etc., these older groups are secret in nature therefore fraternities founded in the 19th century had and to this day maintain a heritage inclining them toward secret behavior. Secretiveness was reinforced by the administrations of several universities that have expelled Greeks early on in the 1800's, Princeton and Purdue are two big examples of 19th century colleges that were hostile to Greeks. Many chapters went sub rosa in the 19th century to avoid persecution.
If a Sigma Chi reads this post perhaps he can explain the big battle Sigma Chi fought to stay at Purdue and how that chapter went sub rosa for years and ultimately opened all public universities to the greeks.
I don't think the mumbo jumbo/obscurantist issues mean as much today as they did 50-100 years ago. Most orgs. simply maintain secrecy as a memory of their past and to celabrate their history.
I think the ideals of an organization are so much more important than whether they are secret .