Detection of simple renal cysts in adults (often called Bosniak 1 cysts according to this hystorical classification) is not uncommon and not clearly related to a pathological predisposing condition.
Different studies all report an increasing incidence age and sex- male related conversely simple renal cysts have a growth rate that is inverse to the patient age. In the paper you cited , phenomena of tubular degeneration, typical of age progress ,where addressed as precipitating factors.
This seem to be a plausible but partial explanation of the phenomenon because hormonal factors are probably involved too
While in some hereditary diseases a clear relation has been found between the cysts growth and hormones for example for ADH (antidiuretic hormone) in Autosomal Dominant Polycystic Kidney, we have no evidences about the role of a specific hormone (ie testosterone or others) in simple renal cysts development.
Considered the sex- and age related incidence of simple renal cysts one can hypothesize hormonal, genetic and aging factor all determining the simple cysts occurrence and development. In some cases maybe traumatic factors be involved, too
But as we speak of a non-specific, non-pathological condition evidences are lacking.
Also, while looking for AQUAPORINS and benign cyst found this pdf. Wonder if PROF. PIERPAOLO DI NICOLO hinted on this: http://en.wikipedia.org/wiki/Aquaporin_2