The vedas have 6 angas, namely 1)Siksha 2) Vyakarana 3) Chandas 4) Jyotisha 5) Nirukta and 6) Kalpa. Siksha explains the proper pronunciations of the Vedas, Vyakarana explains the grammar of the Vedic words Chandas explains the metres of the various Riks and accoustic science assosiated with this. Jyotisha delas with Universe and the movement of planets and stars around us. Even in Jyotisha, there are 2 parts(which is not in to the focus of the subject) Nirukta contains the Sootras or formula for word formation or mantra formation. Kalpa describes the proper method of performing the various ritual mentioned in the Vedas and its practical application with clear cut riders. Vedas should be learnt in this above mentioned way and not from websites or from McCauley's system of education.
So the mantras that you hear and you mention as useless or "not suitable for today's life is just a small drop of an ocean.
There are things around us very far beyond our imagination and just ridiculing something without even knowing what it is just childishness. I dont say, Thriukkural or Aathi Chuvadi is inferior or superiour....I respect both Vedas and these Thamizh scripts for I know, both have tremendous amt of good things in it.