Shruti Vs Smriti

[Nanda Kumar]

I just finished reading a commentry on the Bhagavat Gita by C.
Rajagopalachari and couldn't help noticing the shift in thought from the
the Upanishads (translation by Swami Prabhavananda). The Gita seemed
more to accomodate the changing times and even a bit linient and
understanding in it's teachings.

Where the Upanishads says, those who desire material life and  to have
offsprings are condemned to a world of darkness, the Gita says it's not
really necessary to give up the normal life. For even in day to day
life, if one performs his/her activities without any attatchment to the
outcome, without self-interest, that itself will lead to Karma Yoga. And it
also says people should be very careful about renunciation et al, for
actually they would only be deluding themselves and their desires
forcibly controlled would only fester and grow out of proportion. And
that renunciation and the control of the senses should be done in a
gradual manner thru practice.

Where the Upanishads mentions only the Brahmans and the Kshatriyas
eligible for Self-Realisation, the Gita allows women and the lower castes
too. Also noticable is that the word Brahman is substituted with Brahma.
Did the fathers of Hinduism, feel that the brahmans or the brahmins were
getting too big for their boots and realize the problem with casteism?

So my question is, why is the Shruti given precedence over the Smriti, in
this case, the Bhagavat Gita?