Battle scanners are a band-aid solution. Long War has more pods in most missions than vanilla, so moving up aggressively gives you a higher chance of activating pods. And those pods are actually a threat throughout the game, unlike in vanilla where you can roflstomp them mid-to-late game with 100% crit squadsight double tap snipers. Battle scanners help you plan your engagements, but don't fix the underlying problem that Long War is campier than vanilla. And it's not like battle scanners are unlimited, either.
Long War itself seems to promote a more passive style of play, with its myraid of perks, weapons, etc. that give bonuses to not moving: Infantry, LMG's, Battle/Heavy Rifles, Platform Stability, Rocket Scatter mechanics. Sure, you have Assaults and sometimes Scouts, but pretty much every other class is long-range oriented. When the majority of your squad gets bonuses from staying still, you can't engage properly when moving up aggressively. There's a reason why the most popular strategy for dealing with landed large UFO's in Long War is sitting behind cover and spamming alt-O until most pods are dead. Moving up is a huge risk.