Because it was the first step toward upgrading the min relay fee to 0.5 as well.    It is a way to raise revenue while still allowing market makers to have a discount. 

I highly doubt people avoid transactions because of the fee.   Lowering it wouldn't increase adoption, but it would lower revenue.

As stated in another thread, the discussion is about the reasons for having 0.5BTS per tx .. the origins of the 0.5 have been to be able to pay for the servers that run the delegates ... with the 3% delution and tx fees beeing burned .. we might reopen this discussion ..

at least we should have a good reason to have the fee at .5 tx althought the min. relay fee is 0.1

Lowering it to .1 is not just for voting, that is the cost for any transaction.

Please discuss for us noobs...