I'm not current on this stuff at all, but I think planarity mattered more in the Mead-Conway era than today. Modern chips have lots of separate metallization l

I'm not current on this stuff at all, but I think planarity mattered more in the Mead-Conway era than today. Modern chips have lots of separate metallization layers so you can avoid crossings. Vias aren't free, but they exist so you can use them.