Taking a very small recent sample is just plain ignorant of basic statistics. Especially when if you went back just a few more years, you would find absolutely no advantage and someone equally as ignorant of statistics could use those years as proof of it being a DISADVANTAGE us to a long putter. IT is simply very ignorant of statistics to think that Bradley, Haas, Webb and Els' victory proves anything. Especially since you say, such a high percentage of people are using long putters. Meaning it is not that big of a statistical anomaly for there to have been so many long putters in such a short sample.
Imagine pulling cards out of an ordinary deck. Any clubs you pull represents a long putter. (25% of the total population...so less than 27% that you say used them in the 2012 British Open. Pull out enough and you would expect it to be about 1 in 4. Pull out just 8 or so, and you very well may get 4 clubs. Half of the sample.
Bottom line...to anyone with more than an 8th grade knowledge of statistics, there is ZERO evidence of it being an advantage. The rules makers just overreacted out of sheer ignorance.
Hell...look at the 2013 British Open. Won by a short putter who had his best putting season in YEARS...just after switching back from a long putter. The long putter sure didn't help Phil.