Well there is no way to get around that fact the GeeDubs only changed their stance due to
DE players whining. Like I understand why they were whining, if I had an inherently broken dex and one of my only cool unit combo's was nerfed I would be mad. Imagine if Wyverns had a point boost and my flyrants were no longer allowed two twin-linked brain-leech devourers.... I would be equally mad. However it would be fixing some
OP units in a book where they are among some of the only rational options available to their players.
However the main issue is it's not fixing the core issue with the army or the rules. All it is doing is making a stupid rule decision to help soften the fact the
DE codex sucks. And as you highlighted.... how does it make smoke launcher users feel? when mixed with the 6"+ rule for fast skimmers, it's completely hypocritical. 12" straight movement vs 6" erratic movement.... which one snap fires?

The issue here should not to buff one single unit combination, but to make the rules consistent. If a vehicle has to snap fire.... the passengers bloody well better have to! It makes it easy and simply to remember. If you want to add things fine, but don't fill it full of exceptions and contradictions.