I've mentionned it various times on this forum: the second aircraft that crashed into WTC nearly hit
Midex 7, another airliner in approach above La Guardia airport
There would be a major difference, that is, visual (and psychological and media)impact.
First aircraft took everybody by surprise (except
the Naudet brothers)
Third aircraft - into the Pentagon - also took everybody by surprise
and only a crappy surveillance camera caught it
As for the fourth aircraft - it crashed in the middle of nowhere,
so no image either.
But the second aircraft (into the WTC) was caught on tape by
all medias that were filming the other tower and the other impact. It is the true, iconic, and terrifying picture of 9/11
If that aircraft crashes over la Guardia - no picture either, or not as terrifying as OTL second crash. Psychologically-wise it is only seen as a midair collision, something that, unfortunately, happened before.
To make a long story short: if the second aircraft miss its target, you lose 9/11 most psychological impact