I think you have misread my intent.
Negative side - to choose to marry and have a family?
It is an impossible choice for some and oppression of their sexuality through abstinence can lead to psychological damage.
I am not speaking of homosexuality here at all but of normal heterosexual males - who are also completely devoted to serving their church.
Additionally I disagree completely that repression of an active sexual life can "change" a heterosexual male into a homosexual male - that is incorrect and misleading.
What repressed sexuality can do is cause psychological problems for a heterosexual male, however the church has shown it to be a problem - but an insignificant one.
I cannot justify the request for "non-marriage" for priests however, but that is my belief only and I don't expect anyone here to agree.
The damage may be cause by longing for what one cannot have and by idealiizing what one cannot have. Marriage is great, but do not many men feel equally oppressed by the need to be faithful to one woman for forty years? Staying faithful is staying faithful, and that is "impossible" for many men.