We have a house with two 1970-ish wings which have dirt ventilated crawlspaces, and I'm wondering if I should seal and insulate the walls of the crawlspaces as per current science.

One is ~600 sq ft, 0 to 3' exposure. 1.5-2" of some sort of fiberboard nailed on perhaps 50-75% of the walls (not tight though). Floor insulation has been compromised by humidity and damage; probably 70-80% insulated. Carrier 2-stage air handler (2.5 ton) and first floor ductwork runs through it (R5.x solid plus R6 fle (short runs). Vents (closable mostly) plus an old fan unit (dead). Floor had been damp on uphill side, now space should be less damp (6mil poly recently installed).

The other is perhaps 700-800+ sq ft, similar construction. Older system (Trane 10 SEER) in the crawl; evil internally insulated hard duct plus longer flex runs. Very short return (floor). Ditto on floor, though this was the wettest by a long shot; we put in uphill-side drainage at the foundation bottom plus poly. wall -4 feet (ground 4ft above top of crawl) to 4 feet.

I could
(a) leave it alone, fix floor insulation (redo in first section, probably repair in 2nd.)
(b) seal and insulate crawls, plus dehumidify if needed in the summer. Perhaps remove (some) floor insulation.

Suggestions? Is it worth it to retrofit if the current floor insulation is iffy or in need of replacement?

What about termite inspections? Do I need to leave an inspection gap? Local insulation guy (generally good, does energy audits, etc) was kinda confused by the whole idea; they can seal/insulate (spray foam) the walls, but hadn't given any thought to termite inspections.