dallas were the first to use staggered lugs. the reasons are quite convoluted
although shallow toms can demand demand offset lugs, the simplest solution would have been to use snare lugs, not offset lugs.
so the real question is "why didn't they just use snare lugs on shallow toms instead of adding the extra expense and weight of offset single ended lugs?"
the answer is that there was a desire to make drums look 'american'. although uk drums traditionally used single ended lugs on floor toms (except dallas carlton) they used double ended (snare) lugs on toms.
this made their designs look 'dated' and 'un-american' hence the move to single ended lugs on tom-toms. the dallas lug was too long and HAD to be offset on shallow shell toms. they simply carried the offset to the floor tom for consistency.
a further example is why dallas carlton dropped the 'king' brand and used 'president' - americanisation.
B&H used offset lugs on their piccolo snare drums, and on their really shallow snare drums they just machined off the points of the bullet lugs, just to make them fit(!) this was done because they never ever bothered to make a double-ended version of their bullet lug. they did develop double ended lugs for their rogers snares, and later nu-sound snares.