I think the thing about the read option is that it's like any other post snap read-based system --- to use one example, option routes which are dependent on coverage -- these things will always be difficult for a defense to stop if the offense makes the correct read. Since it's reactionary to the defense's decisions, the offense is almost always going to be at an advantage simply because they are deciding with more information. Either answer could be correct on any given play.
The only real weapons the defense has against a read-based play are a. hope the offense executes it poorly or b. disguise your defense for as long as possible in the hopes of achieving item a. (Ie, combo coverage on one side of the field to hide man or zone and take away a receiver's read.)
I read somewhere that a lot of teams are just trying to counter this by confusing the blocking schemes on the edge with unconventional stuff like having ends stand up, or switch places with the tackle on a stunt, have safeties fly up to take contain, etc. Basically, since they know on any given play the offense wants to leave one man unblocked, normally the guy with contain or QB responsibility, defenses are hoping to be more deceptive and unpredictable about which position becomes that unblocked guy.
Gap responsibility and "assignment football" are obviously the keys to stopping it on a macro level, but on a micro level a lot of teams are going to try to do a lot of East Room line shifting and user audible cheese, which will at the very least delay the time it takes for the line and quarterback to identify the proper "read" man.
Is it a fad? No, not really, but it's something teams are actively trying to counter so it will see some ebbs and tides in effectiveness.