The lowlanders were always suspicious of the highlanders an thought of them as uncouth, and often cattle thieves (at best). As punishment during the covenanting times the "highland host" were quartered upon the recalcitrants of the south-west in the hope that the cost nuisance value and collateral damage would bring about a change of spirit.
It is hardly surprising that the lowlanders resisted tartans. It was only when Queen Victoria made tartans into a fashion thing that they became popular with the social climbing set.
... but all is forgiven, we are all Scots now and the tartan, bagpipes and whisky are all part of the Scots heritage.
Lowland Scots heritage seems to share the fiddle, jigs, piano accordian and general outlook with the Irish.