There is no GPS in the bracelets. There is active WiFi RFID and some folks have postulated that that could be used to track guests. "Could" be used. No-one has provided any indication that Disney intends to or would have any viable reason to.
Even you have referenced their silly idea that characters on rides and in meet&greets will use guests names: that requires knowing that the guest is present in a particular place at a particular time. Knowing how guests move through the park in finer detail, and how that correlates to guests' demographic profile is the entire point to the system. It happens that entrances/exits to buildings are the easiest and most accurate way to track RFID tags as they are moved around (and the easiest to hide as well). Doesn't it seem like every shop and restaurant on the property has had a facelift/remodel/repaint in the last 2-3 years -- you really think that there aren't RFID readers already in place?
Actually, most apps use the phones geo-location to put a dot on a map that's already on your phone. Sending data back and forth is limited to very specialized apps, such as "Find My Friends". Even if they were to put out an app that provided real-time geo-location to Disney, the computer programming and processing power to accomplish what you're proposing across the full WDW property and encompassing all guests simultaneously is way beyond the capabilities of what could be done for the $1.5 Billion they're spending on NextGen, let alone all of the other things they're including in the NextGen program. Yes, it "technically" could be done, but this is an organization that can't keep their internet sites functioning for any length of time.
While geographic data is somewhat specialized, its not all that rare, nor is it particularly difficult or expensive. There's a distinction to be made here between Disney knowing exactly where you are (to the nearest meter or so) using geo-location/triangulation systems and Disney tracking approximately where you are (which ride/shop/restaurant) by knowing the last doorway your RFID tag passed through.
Typically, the data-mining operation does not work with real-time data very much, because it is working with large volumes of data and the real-time data is tuned to deliver small amounts very quickly. The information that they are using for data mining purposes will eventually be aggregated across very large groups of visitors, so the specific location at any given point in time isn't really worth a whole lot. They do want to know how to generalize behavior across large groups, and the general location is really what they're after. How much time to guests with a specific profile spend in shops along main street at various times of the day or different times of the year, for example.
To extend that tracking capability to a real-time WDW-wide equivalent of an air traffic control interactive display could be done, but at great expense and for no profit-based reason that I could fathom. "Could" be done...
I agree with you on this point. While its possible to do this, it does blow up the budget on the real-time system, with very little discernable business benefit. They are gathering millions of datapoints each day about guest traffic through the property. The real time database is what receives the guest traffic data, checks the admisstions & exits at the main gate, and processes the fast-pass returns (does guest #12345 have a fast pass for this time window: if so, tell the reader to light the green light, otherwise tell the reader to light the red light). To keep up with peak traffic (mid afternoon on a busy day) requires fairly dedicated equipment. By design, there is a very limited number of processes that access the real-time data, in order to keep all of those processes as responsive as possible.
I think that this is one of the things that people freak out about when they imagine geographic tracking: they've seen too many episodes of CSI & too many spy movies where this kind of stuff happens in real time. In the movies, this happens (at worst) with about 1-2 second refresh rate (they sometimes show the dots on the screen jump every couple of seconds). The system is essentially dumping its entire contents every couple of seconds to a screen display: in real life, this would bring the responses at the fast pass readers to a crawl and seriously inhibit the ability of the system to keep up with the incoming data traffic.
PS - You're entirely correct to doubt Disney's ability to actually pull this off, given their inability to keep the website and hotel & dining reservation systems working reliably.
