Again, something that's DM dependent. This particular campaign had us dungeon crawling for much of it. In a dungeon crawl, hallways and doorways create natural choke points that can advantage one side over the other. The few times we were outdoors was against 1-2 large/huge creatures, so while a front line didn't exist, it was fairly easy to simply engage the enemy away from the ranged PCs.
In addition, this guy was a massive meta-DM who looked to find ways to minimize/negate player abilities (so it wasn't just me). On the other hand, when I DM the monsters attack based on the intelligence of the creature and the situation at hand. One player had both the protection fighting style and the Sentinel feat, and she got a lot of benefit from both. This shows it goes back to my original statement that it's very DM dependent, and many players are wary of such abilities unless they already know how the DM intends to use them.