Agreed. I was rooting for London, but I am getting excited about Windsor mostly because of the carriage ride.
With that being said, I stand by my point that Harry's wedding should have been at Wabbey and trying to cram a senior royal's wedding into Windsor was a bad idea, even with it being pared down. Securing the Mall is done several times a year for other royal events and the police are pros at it in London. Trying to cram even a fraction of the people they expect (and I think 100k seems a little high) into Windsor will be a nightmare.
At the end of the day, if Kate and William or Edward or Sophie were to get married today in London or at Windsor their security costs would also be outrageous. This is just the name of game in today's world. We use taxpayer money ALL the time for big sporting events which are technically subsidizing private business. A royal wedding is a national event with national/historical import (especially this wedding). The police have made decisions about security independent of the wishes of the bride and groom. The carriage ride may add to costs, but at the end of the day it is the police going above and beyond to ensure safety--even if some of the measures are likely overdone.
Why people whine about security costs is beyond me. Maybe because I live in the States where POTUS' security cost 100s of millions a year (and even more with this President...), but the purported cost of this wedding seems small for what will likely be a large event with lots of public involvement.