I’d argue that this is actually a flaw in ANH, and the evidence is in ESB. Part of what makes Luke’s desire to fight Vader so compelling is precisely because he was robbed of this moment in ANH.
So yes, a flaw, but one that ends up working to the trilogy’s benefit overall.
Well that’s a fair argument but I’d nitpick and say it’s not Luke getting the lightsaber that sets that up, but rather Ben explaining his father’s death.
I’ll always argue that SW works perfectly on its own but certainly there’s potential in the Vader storyline that is left unfulfilled (and then later successfully fulfilled in TESB). It is, of course, the one hanging thread of the film.