This is India, not England. Spin is this team's main bowling strength.
What great thing have Indian seamers achieved away from India, to be better than the spinners? Can't think of any. None of them have 5-wicket hauls, except Zaheer's 3 (including 2 on that custom pitch) and Agarkar's gift-wrapped 6-wicket haul. Look at the averages and number of 5WI's. Not home or away, but overall.
As you have seen on their tour of Australia, the seamers were of no use. They lack the experience. Besides, when they get good pitches, they bowl too many short deliveries and get carried away, thus wasting helpful conditions. If the pitches are flat, the very purpose is not served. No point picking seamers just to exploit the conditions. Just get bowlers, spinners or seamers, who can get the most wickets. I don't care how seamer-friendly the pitch is, I'd still pick a spinner over Nehra or Zaheer or Agarkar, unless they are really great bowlers.
If you look at the better bowlers in India, they have been spinners. They are not picked just to make the numbers, but because they are better bowlers. These days, except in the Australia tour, the spinners have been more effective.
Mishra should not be rushed, but you still need backup.