Why Unit Base Your Army?
A simple 25mm square bases simply doesn't have that much room, especially once you attach a figure, and once of the downsides of individual basing is that the little details can get lost within the mass of the unit. The best part of basing models as a unit, rather than individually, is that you can go above and beyond just adding texture and vegetation- you can making highly themed bases or creating dioramas within your army.
For systems which require you to remove individual models as casualties unit basing can very problematic during games, which is you will quite often see mini-dioramas aka Unit Fillers in many Warhammer Fantasy armies.
Kings of War is quite different as a massed battle system, in that the rules and game mechanics are specifically designed to favor basing entire units on a single large unit base. This is because you don't have to remove casualties and each unit has a specific footprint and height within the rules. This makes it the perfect system to really go to town with extra details and mini-dioramas for your unit bases.