Why do pandas avoid meat?

Came across an interesting article on 'how it works-amazing animals' as to why pandas have adapted to eating a diet of 99% bamboo, eventhough they are technically carnivores. Pandas are genetically unable to convert cellulose from plants to energy, so they must eat upto 38kg of the fibrous plant(panda's gut has developed a thick layer of mucus to protect against bamboo splinters) to get enough calories to survive;the task requires 12-16hrs of foraging and eating. Why go through all this and avoid meat?
Recently sequenced genome of pandas have provided clues to this; a genetic mutation makes them unable to taste flesh.Fossil studies have shown that panda's ancestors swapped meat for bamboo somewhere between 2-7 million years ago-perhaps due to a major environmental event wiping out their prey. Being caused to change their diet may have caused the gene responsible for tasting savoury foods to become obsolete, and without it they might not have wanted to eat the tasteless meat even when it became plentiful.