Why is it, that converts from the ICCEC or other protestant Communions in apostolic succession have to be ordained anew or at least sub conditione?

Bishop Ferraz who was consecrated Bishop Duarte Costa was received in the roman catholic church, even as a bishop. Without a new ordination or sub conditione.

http://en.wikipedia.org/wiki/Brazilian_Cat...postolic_Church

A similar case was Alfred Seiwert-Fleige who was ordained a priest for the Carmelites of the Holy Face in early 1976 by Archbishop Ngo Dinh Thuc, and consecrated a bishop around 1980. He left the Palmarian Church in 1981 and was finally reconciled as a valid clergyman to the Roman Catholic Church in 2001 by Pope John Paul II, and concelebrated at a Papal Mass at St. Peter's Square, Rome, after which he was publicly embraced by John Paul II from the papal throne.

http://en.wikipedia.org/wiki/Palmarian_Catholic_Church

The palmarian church is clearly a schismatic Catholic sect with its own pope, Peter II.

It seems reasonable to consider that Rome would certainly evaluate each case, each person individually on individual merits. What of the background, health, balance, education, formation and faith of each case?

Would not the Methodist Church do likewise? Which is to say that there would likely be an evaluation of a candidate who may be "transferring in" from a denomination with which the Methodist Church has a relationship which might allow such a "transfer". It is hard to see anyone transferring from Bed, Bath & Beyond to Linen N Things without a similar process of individual evaluation. I don't mean to make light by using this comparison, merely intending to make it clear.

Apostolic succession what ever the credential is certainly not an "automatic".

I agree here. In my experience, each case is evaluated on an individual basis.