Meta affect of Terrain

If a lower amount of terrain is used on your table, or if terrain rules are not used, then units may become more or less powerful than they were designed to be. 

Wizards and Priests have many extra benefits from terrain. Often giving a bonus to cast or unbind, extra summoning ability or powerful spells unique to terrain. Other terrain pieces can hugely benefit characters with healing or unique abilities, the Magewrath Throne for example can be literally game changing. 

Ranged attacks suffer from increased terrain due to line of sight rules and in the same light, so do lightly armoured units and heroes benefit who would otherwise suffer worst from those ranged attacks. 

So for example, if ranged units are highly pointed because not enough terrain has been used during play tests allowing them to rain down arrows with impunity, the Meta has been changed by the lack of terrain. 

As I mentioned in a previous post, you should have 8 pieces of terrain on the table on average and each of these should either use the terrain Warscroll it represents or roll on the scenery table. 

Now this is quite a subjective topic which is not easy to determine the true differences and whether it makes an impactful change. But a good example is Clash Comp, which specifically does not use the Terrain Warscrolls, so you must assume the pool system is biased towards terrain having low impact on the units in games. 

In summary, terrain influences different units in different ways, depending on what system you use to select armies some units will be more or less valued depending on the amount of terrain that system was play tested with compared to how much terrain you use. 

In the end, the Terrain Warscrolls are fun and create more synergy. If you aren't using terrain, you aren't making the most of Age of Sigmar.