[Taqwus]

Acashic Record does require Conjuration 5 (!), an Astral-3 mage (or an Astral-2 with a Starshine Skullcap / Crystal Coin; more widely available), and a whopping 25 Astral pearls per casting. Most of the single-field divination spells are easier to research (although they're in multiple fields) and often easier to cast (heck, Dark Knowledge is a Death-1). They're also far cheaper.
If you've bootstrapped your gem income to the point where 25 Astral isn't much (note: that's enough for a Juggernaut, or an Imprint Souls, or half an Angelic Host, or a quarter of a Wish..., or 187.5 gold after conVersion to fire gems, etc), and the magical site frequency is rather high, it might be useful to you. Or if you're playing single-player or against human players that are also playing less than brutally optimized, I suppose.
Hm. In Dom I, you sometimes used to be able to *know* that there were at least X magical sites in a province because there were four slots, and when one was found it revealed the site in the slot corresponding to an arbitrary order. If you lit up a site in Slot #4, you knew there were three other magical sites present, and thus it might be a good Acashic Record candidate especially if you lacked the mages to cast the single-site divination spells or you also wanted the holy/unholy sites. The new interface fixes that.