I've noticed it a lot too. Maybe it's partly because the 3-point line was moved back recently. You try to play instinctively in basketball, so if you're used to having a little more wiggle room, it may not be ingrained in the mindset of many players. There's only 40 inches between the 3-point line and the sideline. Seems like players that drive from the 3-point line often take a step back, before driving. That's one of the bigger reasons why we're seeing a rise in players stepping on the sideline, IMO. Coaches need to thoroughly monitor little things like this during practice. Punters know their surroundings when they're kicking out of their own end zone. Basketball players need to have that same sort of awareness. It should not be happening as often as it is.