Abilities that reset cooldowns create potential choices for classes to refresh their cooldowns on demand so that they can be reused; the timing on using this can often result in their victory or demise. Using them for simply zerging in and blowing all cooldowns twice will often not result in the best of outcomes as this can quite often be countered by your opponent.
You have to remember that having an ability that resets cooldowns on demand such as Preparation, Cold Snap or Readiness does not make a class overpowered or provide them with a greater advantage over others. It is simply another part of their toolkit and it comes with an innate choice, "Should I use it now or save it for later?" this adds an additional skill factor to their class. Do you pop it now to increase damage output and possibly secure that kill? Should you may maybe be save it just in case you need that second defensive cooldown or crowd control in a tight spot? Maybe you should wait until everything is finally on cooldown?
Knowing when and where to use these abilities is a very difficult thing to be able to assess. These are the decisions that make or break and separate the good players from the great ones. Just because some classes can refresh their cooldowns on demand every now and then does not mean that the ability allowing them to do so is overpowered or needs to be changed in some way, it's simply another part of their class, as is the same for other abilities for anyone else.