As you yourself said the main shashtras do not give importance to these rituals. Besides their importance was always relative to the real elements of the true spiritual life. People follow rituals partly because they are full of desires and rituals seem to promise the fulfilment of these desires. Partly it is because of the ignorance of the Scriptures and rituals being external acts appear tangible and easier to do whereas true spiritual movement is largely inner and hence not many are ready to undertake it. Rituals are like the early books of a language where one learns the outer meaning of a word before one dives deeper to understand the subtle nuances. They have a place for the early training and education of the soul struggling in the ignorance. But as one develops they become itself a chain and a bondage. It is easier to locate God in a temple with certain physical forms and thereby connect with Him. But to connect with the Divine Presence in everything requires a certain degree of inner development for which many are not yet ready.
Affectionately,
Alok Da
