We used to use animals to carry and haul for us, as beasts of burden, until technology re- placed them. Technology is now coming up with other ways to exploit these creatures. Discoveries in genetic engineering suggest we could use them as live "factories" for producing blood or organs for human transplants. The fact that we kill animals to eat them is the only justified use.
One false assumption is that the animal kingdom is there for us to use in almost any way scientists dream up or commercial companies see a market for. To create animals on a production schedule to be born, grow and reach maturity for sale and slaughter at exactly the time we want turns animals into nothing more than a commodity. To say it's only an animal and there are jobs or economic growth at stake seems to miss the point.
From a religious perspective, all of nature owes its existence to God and we all have a responsibility to rule it and look after it. We have to recognize our limitations, as we are not perfect and have imperfect knowledge. Nature is not ours to do whatever we like with. We are also creatures, along with all other created things. Our use of animals shows us we need a sense of "holding back." These are living things which demand respect. The Bible declares that God created variety, making everything unique. To clone something or someone reduces it to a blueprint, while God seems to have made a point of doing the exact opposite.
Then, what happens once cloning is spread to human beings? We will begin to create genetically perfect humans. Who will have the powers to decide who does or doesn't get cloned? Which traits will be eradicated? Will we "grow" humans for menial jobs and labor?
The medicinal advantages to cloning are incredible, such as brand new organs without waiting lists for donors. But do we just discard the artificially produced humans from which the donated organs came?
With so many questionable areas regarding who does hold the power to decide and with such a high probability for abuse, we can't yet handle this incredible new-found power. Until we can develop sufficient parameters and at least understand this technology, we have to discontinue cloning.