Genetically modified animals (GMA) are commonly used in laboratories for experimentation. I consider that a good thing because these animals are the key to progress in medicine. For example it is because tests were made on these animals, their ability to adapt and their resistance, that we were able to cure some diseases such as influenza, which was a great concern. It is also thanks to these animals that we can keep the research moving towards finding a cure for rare, genetic or severe diseases (e.g. cancer, Parkinson's, Alzheimer's) and study the side effects of some molecules before releasing them to the open market. So, whatever the study is, GMA plays an essential role.
It should be known that scientists working in laboratories are very concerned about ethics and the welfare of animals : they handle and prepare them carefully so that they could be as less stressed as possible. Moreover, if they work with animals, it is also because they like them !
However, cosmetics and clothing are unhealthy luxuries and I am therefore opposed to the use of animals to those ends.
I would conclude by saying that without GMA, there would be little to none progress in medicine.