To be the devils advocate:
The beneficiars are the manufacturers of said equipment and warehouses, which pay their employees and their suppliers for the work done, who in turn will pay their employees as well. And by the way these employees will buy houses, cars and food from other companies, which .... Need to go on? And every part will pay some tax as well.
The investments are probably paying themselves off. One can debate if the service delivered is a usefull one, but in the end it translates to 'real' economic value in terms of production of other goods. Because economy is about pumping money around. The faster, the better. And if the investment pays off really good, then there is money for investing in improved banking services as well. A win-win situation here.... Ok, I'm a bit sarcastic here.
So, my conclusion, yes, there is a cost, but yes, there is also a benefit to society in terms of economic activity (real). And I think it is better to focus on the unfairness part of it, which is on the part of the big, fast, but not so fast traders. But it is a rat race and I'm confident it will be sorted out. The end result is no one will make money this way and that again there will be a fee asked for trading. Problem solved.