Pillar humping is ridiculous.
There are better ways to do LoS without resorting to pillars everywhere, e.g. walls, ramps and bridges.
Dalaran arena is a good example. Blade's Edge would also be a good example if it didn't have the two pillars on ground level.
---------- Post added 2013-05-09 at 11:14 AM ----------
"No pillars = flat arena without LoS" is a strawman argument. It's not true.