In my opinion, futures trading has become much more difficult in the last 15 years due to a few reasons.
First, the players have become far more sophisticated.
Second, there are fewer and fewer sustained long term trends, particularly in currency futures and commodities. All the long term trends seem to be in equity markets.
Third, most trends are much more choppy than they used to be.
Lastly, the day to day volatility is greater than it used to be. As a result, position sizes have to be smaller, making it more difficult to exploit trends when they do come along.
Must my two cents.