I don't think your statement on national focus and 1810s is too far off. The fact is about 65% of our billets at the O5 and above level in CONUS and HI are in the beltway (from 2014 NFOSES preparation, doubt its changed much). Look through the IWOL; it's pretty clear where the center of gravity is for the community - it isn't the fleet concentration areas, that's for sure. This, by the way, isn't wrong: national money provides for a good portion of our community. Looking at missions performed at the big four/five, it is heavy toward the national side - simply a matter of how the community perceives its charge and future potential. Look at FIOC numbers vs total numbers at that NIOC - seems pretty clear.
1820s and ITs are much differently employed and for different reasons. They and their functions are ubiquitous, at every command, with O5s and O6s prevalent in fleet concentration areas and throughout staffs. Where we are represented with maybe one LT or a Warrant (LHD), the IP community may bring an O4 Dept Head (C5I), APDO LDO/warrant, Commo (LT), and maybe even an A/C5I. It's the same with afloat staffs (although we are pretty well represented on CSG staffs). Their effort is more central to the daily goings on in the fleet outside of the beltway - everyone requires it, both on and off deployment, at sea and shore alike. Our content is not ubiquitous and not as basic a function. The cryptologic community does have some fleet focused commands- NCDOC and NIOC Norfolk (plus its subordinates) - but like any other dual hatted reality, only one master can be served really well. I kind of wonder if that reality isn't what fueled, in some small part, the move to break up NIOC MD into multiple O5 commands.
Meanwhile, moving in the opposite direction - the other big NIOC is looking for their CO's third hat and C10F wants to take back several ADCON functions from the TYCOM (IFOR). Interesting times; feels like 11 March 1935 and 29 JAN 2010.