that's certainly some of the reason for polls. pure business factor too, the masses love polls, makes em feel important, voice being heard and all... (at least the love polls when they agree, and are interested in polling data regardless if for no other reason than to complain about how biased polls usually are and how the data's never any good, but we keep reading em...)
for those in tinfoil: yes, they are putting out poll results that are fabricated with the intention of influencing public opinion (hey, if 67% of the people think something, it's gotta be true, right?)
a good poll, done correctly yeilds useful data. data is knowledge is power. any good machiavelli would be polling out the yin yang to time his dance of manipulation to the thoughts of the world.