The nicest toners tend to have great luster. However, there are examples where the toning is heavier and it mutes that luster. The grading companies tend to penalize that with lower grades. At that point you look to see if there is any wear and how much disturbances you see on the surfaces (hits, bag marks, etc). I used to have a Morgan that was on par with many MS 65 examples when looking at just contact marks (it had no wear) but PCGS graded it MS 63 because the toning diminished the luster.
I agree with Dennis on this. TPGS do have trouble with the toning/ luster balance. Sometimes, the luster gets masked by the thicker aspects of the toning. In this case, I think the glamour shots of the coin exaggerate the dullness of luster. The quick snapshots of the slab show a brighter coin, and in hand, it is a bright coin, with nice toning especially on the reverse. If toning is too thick, TPGS will definitely grade a coin lower— I have seen many technical gem coins graded as 63-64, when they were obviously gem coins, based on strike, and surface preservation. Album toning like this can be very difficult to grade, as it is hard to envision the coin’s surfaces as if they were brighter. However, since virtually all of the Morgans were dipped, the myth of naturally bright coins sort of spoil us. A 100+ year old coin will tone, and often not attractively. The 50-60 year old Franklins have a different kind of toning, and we’re often not dipped, though some of the more brilliant ones were not naturally screamingly bright.