Some links that already talk about this:
https://forums.autodesk.com/t5/inventor-forum/drawing-balloon-alignment/td-p/5761543
https://forums.autodesk.com/t5/inventor-forum/balloon-magnetic-line-in-drawings/m-p/8386910
https://forums.autodesk.com/t5/inventor-ideas/align-balloons-to-an-edge/idc-p/5407633#M6430
SolidWorks and Solid Edge already have this. I have found it incredibly useful for neatness--especially when adding more things after ballooning (e.g. dimensions, text, etc.)
Each Magnetic Line should have the ability to be selective in what type of elements gets 'snapped' to each magnetic line (e.g. balloons onto one line, text onto another, etc.).