Ritual and mythology have their place as long as they support an ideal worth having and aspiring for.
We all have our daily rituals. Like getting up from bed, going to the toilet, brushing our teeth, having a shower, getting breakfast. Rituals are needed in daily life, but we need those rituals that will actually bring us great benefit.
We also have our mythology, common stories we tell, like fables like the hare and the tortoise. The stories from Greek mythology are used commonly in philosophical literature to bear our certain points. To this end, the Puranas in Indian literature are useful, so as long as they bear a philosophical truth or a moral worth teaching.
The problem is that in Puranic Hinduis, the ideal is set very low. For many Hindus they are worshiping an actual god. Vaishnaivists worship Vishnu(Lord Krishna according to them) who lives in heaven(Vaikunta) and who rewards and punished, and incarnates on Earth from time to time. Many are awaiting his latest avatar Kalki to come and solve the worlds problems.
Thus they live in a fantasy world and have the childish temperament to back it up. They are simple people of faith and make images of god in their own image, attributing their own qualities onto him. They like fun and frolics, and so does their god; they get angry and sad, and so does their god. They are people of the book, literally reading their scriptures and believing everything within it and reading metaphorically anything within scripture that modern science has disproven e.g., the Puranas mention that the moon is further away from the Earth than the sun. So is Sarva going to accept this fact? Nope, he will reinterpret it.
Sound familiar? Every religionist does that. These people are not morally, intellectually and spiritually any better than an ordinary person, because religion for them is nothing more than a belief system.
Their low ideal is backed up with low mythology and low ritual. Bizarre stories like flying monkeys from millions of years ago, talking fish, immaculate conception. Bizarre rituals like crawling up the stairs of the temple of their god up and down, fasting a number of days to appease their god, ringing temple bells, bashing in temple baths, subjecting themselves to pain or mortification to win the grace of god.
Low ideals, low mythology and low rituals leads to low people. History will testify that religious people have not proved to be any better than non religious people, in fact in most cases religious people have been the most murderous, deceitful, immoral lot. It was a religious people that burned hundreds of thousands of ‘witches’ It was religious people that in modern day India slaughtered each other during the partition. It is these religious people that cause stampedes in India and trample over one another.
Hindus are mostly made up of these low, simple and common folk today.
Then there are high ideals like self-realization. High ideals are backed with high mythology and ritual. High mythology are like the stories told in the Upanishads or the Yoga Vasistha or the Mahabharata(including the Gita) and Ramayana which explain complex philosophical concepts of Vedanta in story form and make them more enjoyable, palpable and understandable. The device of using stories is a common practice known as “Katha” It matters little, whether the story is fictional or non-fictional, but the message behind the story matters. This is why “Purana” is named as the 5th Veda. But that has nothing to do with the sectarian Puranas that we have in our hands today.
High rituals are rituals that will contribute to the ideal of self-realization: like self inquiry and introspection, contemplation, meditation, pranayama, asanas, mudras, bandhas, mouna, mantra. Practices that will actually produce REAL results. Climbing the stairs of a temple barefooted on broken glass while chanting “Hare Rama Hare krishna” probably wont do anything for you to bring you closer to self-realization, but a round of alternative nostril breathing will definitely calm down your nervous system and work towards purifying your body and reducing anxiety, depression and strengthening your senses.
High ideals, high mythology and high rituals lead to high people. Again, history will testify that if it were not for spiritual visionaries in their respective societies enlightened traditions like philosophy and science would not have been born. The Rishis of India laid the foundation for a glorious intellectual culture in India which lead to the birth of great minds like the holy sages of the Upanishads, Panini, Buddha, Mahavira, Patanjali, Kanada, Gautama, Bharathari, Vyassa etc
In Greece it lead the birth of Pythagoras, Socrates, Plato.
A point to be noted how Indians in the past were pioneers in science and philosophy. Since, the onset of the the Puranic and Bhakti age, Indians are not pioneers in science and philosophy. Most Indians consider the study of philosophy a waste of time today. That is why Indians themselves are a waste of time for the world 
Set your ideal high.