A panda's diet normally consists of leaves,stems and shoots of the bamboo plant,vines(not those kind) and sometimes small rodents. While pandas may have alternatives to bamboo, developing a new source of food can help increase the numbers of pandas.Some of the panda's natural food source is being destroyed due to human habitation and farming. Developing a new food source can help substitute for the loss of these foods.
For years nutritionists have been feeding Pandas bamboo because they thought this is the kind of food that Pandas liked. But it turns out that this is a myth. There is likely already some other food that is better for them and easier for them to digest that already exists.
Pandas were born to eat bamboo, but if you consider evolution, then maybe scientists should try to introduce another food source. It could be that pandas have evolved to be bamboo intolerant because of pollution or other environmental factors. If the species isn't thriving, then scientists should seek an alternative food source.
Pandas have always eaten bamboo. It is not the place of scientists to attempt to introduce a new source of food and change the diet that has always served them. If science were to find a way to help pandas digest bamboo that might be appropriate, but their diet must not be changed.