Well, I guess I belong to the preset abuser club.

I think that having presets available in a piece of software that is referred to as a mastering plugin is a great boon. How one uses the presets is a matter of personal preference.

I think that the presence of presets in any piece of software can be abused (just using the presets and never learning the mechanics of the the software at hand), or they can be used as instructional elements to build off of. I've used both methods to success.

Any plugin that is worth it's salt as a 'mastering' plugin is going to have likely multi-band dynamics processing, limiting, EQ and perhaps even more parameters.

Without at least some bit of guide to using it - it's going to be a useless tool immediately - because of the myriad combinations of settings.

Let's not get into the argument whether or not if you don't know the ins and outs of the combinations of all of these signal manipulations to begin with. One way to learn what they do is by building off of some combination that imparts an interesting character to your mix - a character that perhaps you didn't intend to have to begin with, but actually sounds more interesting than your original.

You have to start learning somewhere. Most likely you don't have a local neighborhood Bob Katz on hand to show you the ropes. A good set of presets can get you off the starting block.