It seems to me that Rorke’s Drift was more of just a footnote to the Isandlwana (Isandhlwana?) battle prior to the Rorke’s Drift action. My guess is that Isandlwana gets historically short changed because of the outcome. The Brit’s don’t like to be reminded of when they got their butt’s kicked.
The Battle of Rorke’s Drift blunted and ended The Zulu’s ability to clear out the British from their land. The Zulus had to stop and clear this position, wasting time and energy they could have used to ambush Lord Chelmsfords relief column. Nowadays we call that blunting thier operational reach.
After Rorke’s Drift, the Zulu lost the initiative they gained at Ishadalwana.