One simple reason to centralize the location of civic assets
It's easier to get there, because extant mobility services already serve those places.
There is a letter in the Gazette, "How about a bus to serve Wheaton library?" which suggests the creation of a special circulator bus to get people to and from the library. The new library and rec center will be about 3/4 of a mile up Georgia Avenue from the center of the Wheaton town center area.
For the most part, circulator type bus services don't get a lot of use (There are two types of circulators, the kind in Downtown DC, Baltimore, and Denver, and more neighborhood-y specific services like the Capitol Hill Circulator. The first type get a fair amount of use, justifying high frequency, while the others tend to have abysmal ridership numbers, although they are very popular. I call them political bus services.)
A special library bus would be pretty expensive for limited use. Downtown Wheaton is already served by a variety of bus lines as well as the subway system. (Then again, bus service already is provided along Georgia Avenue with stops at the library as it is.) While it would be more expensive to build such a facility there, because the cost of land is higher (not unlike some of the issues with the Rockville Library in Rockville Town Center), there would be significant agglomeration benefits.
The letter mentions the circulator routes in Silver Spring (Van Go) and Bethesda (8/8 ball). But I don't think those routes have very significant ridership either.