Considering the lethality of Elites and some units in this game, map vision becomes more important than in past titles. If you manage to get the drop on an unsuspecting enemy, the results can be catastrophic.
I think a lot of people complaining here about balance rarely, if ever, mention if they spotted the enemy first or were caught unawares. I'll see threads about how a certain strat or unit is "imba", yet the so called balance discussion feels like the engagement is happening as if the units arrive into it simultaneously, with both players aware of the same things about each other.
Which... in this game (and many other RTS's) never happens.
Some people ++heresy redacted++ on the game because "it has MoBA influences" and some others will ++heresy redacted++ on the people that say such things. But MoBAs do put vision at the front of centre of skills to master, to the point one player is assigned ward duty. It is probably a feature from that genre that found its way to DoW. And a good one at that, since it makes lethality something you can counter or use, depending on what you're doing in any given moment.
I felt this deeply as I decided to start online with the Kommando. His skills are cool and all, but the biggest value I got from him was the info I got from sneaking him around and informing me how and where I should engage.
Certain AoE combos can decimate entire armies, but for that you need strong awareness of the enemy movement. Defending against AoE combos depends mostly on map awareness.
All this said, how are you dealing with this important factor? Are you bringing builders around with your main army? Spreading them around in the map or putting them into bushes? In team games, are you scouting for the Eldar webway gate and having your opponent lure the army out while you go in to take it down? How are you keeping tabs on that Weirdboy at all times not to be caught unaware? Are you putting enough detection in place to anticipate Space Marine drops? What maps are easier to use detection and what maps make it easier? What other uses have you found for vision?