Why has Indian mythology given forms to all energies. Are all the mythological stories true?
How can Rishis lose control and curse if they are enlightened?
The universe is full of names and forms. The moment you give a name, form also comes with it. And many of these forms were cognized in the subtle. So they continue in the subtle realm.
Now, why did the Rishis (Seers) get angry and curse, I don't know. Usually not every Rishi does this. There were only a couple of them who did this. But every time they cursed, something great happened from their curse as well. That is why it is said, the anger of the enlightened also, does something good for the society, whereas even the love of an ignorant person does some harm.
A wise man's anger also is beneficial. He cannot do any harm, he only does good to the society.
So every time a Rishi cursed, it turned out to be a very big boon to the population.