For the record, greater diversity is in a very general sense a good thing. But bear in mind that it isn't always so good. For instance, consider that a wild harvested product can contain all sorts of pests and pathogens, both bacterial and protozoan, from Vibrio coralliilyticus to Uronema marinum and so on. Is that "extra diversity" beneficial too?
Furthermore, the main point of bottled bacteria is not for diversity per se. In fact, it's actually meant to contain only a few (or even just a single) species because it's used for rather specific purposes.
Think of it this way. Let's just say there is a Species A that is abundant and ecologically important on healthy wild reefs, but is NOT so abundant in most reef tanks. Why would it not be abundant in reef tanks? Because captive conditions favor its competitors such as Species X. Now, you might be able to re-set the microbial community to something closer to Nature by adding a concentrated inoculum of Species A from time to time. In that case, you're just tipping the balance towards a favorable condition, similar to if you were adding any other product to replenish calcium, or trace elements, or whatever. Would this work with live rock rock or sand? Not so much. First, you're not going to just keep adding sand or rock for that specific purpose ad infinitum, unless you want a tank that eventually is filled to the rim with sand and rock. In contrast, you can add as much of a concentrated bottled product as you need to get a desired cell density fast (immediately, actually). But more to the point, if you're adding a "high biodiversity" rock/sand product that is adding both Species A and Species X, then you've not really shifted the balance. In fact, you may not necessarily have added any Species A.
I'm not saying live rock or sand is bad, by the way (though it can be bad, depending on how/where it is collected and how it's stored/handled). As an ecologist by training with a huge interest in aquarium microbiology, I'm all over live rock/sand and appreciate the many beneficial microbes they can bring to the table. My point is that those products, and bottled products, are two distinctly different creatures. Comparing the two is like comparing nori and Reef Roids. They're not mutually exclusive.
