If your question is specifically about beatification in the modern Catholic church, I can't really help you very much; but I'd contend that, for much of the history of the Catholic church, beatification has been a fairly standard aspect of many influential church figures. Take for example Ambrose of Milan, who not only excavated and claimed as martyrs two bodies which he claimed as being Gervasius and Protasius, but had his own siblings beatified (they are still venerated today) and was made a saint himself; to my knowledge, this all took place without significant opposition, or at least opposition which is available on record.

Another early example is that of St. Gregory of Tours; by making as great an effort as possible to associate himself with saints (particularly a famous predecessor at Tours, St. Martin), Gregory created the extended impression of his own holiness, with the ultimate effect that he too was quickly canonized after his death. In other words, there have certainly been saints who were beatified without contention; while I can't comment on the Catholic church from the eighteenth century onwards, this was largely the case before then.

The opposition is provided by the church itself as part of the checks and balances of the process. The term "Devil's Advocate" comes from this: http://www.newadvent.org/cathen/01168b.htm

The fast track to sainthood is martyrdom. For martyrs the pope need only recognize their martyrhood and they are automatically a saint, skipping the usual process of finding widened and devils advocates and such.