Because where gravity wells are concerned, center of mass is everything. Mass lock is not proximity lock.
And you can get mass locked by planets, moons and stars. Fly close enough and you'll see.
So I wouldn't say it's an issue. Working as intended. As for colliding with the tail end of large Orbis stations on supercruise exit, that is an issue, and it was introduced when they reduced the warp-in distance to 8km from 20km due to much whining. Some stations are longer than 8km. Boom.