When building an adventure or an entire setting I'm always wondering how much of things that are magical or mundane I should include. Describing a setting has a lot more to it than simply rolling out lines of descriptive dialog. Encounters describe the setting as much as they provide opportunity for challenge.
When including encounters that are meant to be descriptive over tactically challenging the DM has an opportunity to offset other encounters. An endless stream of mostly hostile oddities serves to enforce simple game playing and serves to diminish anything unique in a host of magical monsters.
If your game takes place in the dung age (for example) encounters presented to display the setting over a tactical purpose lifts the background into the foreground and accents the more intense tactically challenging situations. Filthy harlots, processions of lepers, and roadside prophets (typically with no more power than their ravings)are a strong offset to wandering sorcerers,misplaced drakes, and misanthropic humanoids that do more than an enldess stream of encounters that pop out exp and gp when they are bashed by the PCs.
Encounter tables as usually presented focus on the intense and immediately dangerous and this really reduces opportunity for exploration and discovery. Random encounters with hostiles present little more then speed bumps that consume resources and delay progress if that's all they ever are.
There of course has to be a balance between the mundane (setting specific) encounter and the more magical and monstrous ones. Too much mundane and we lose the magic that draw us to the games; it's really a balancing act to keep the players anticipating what may come next.
A setting full of weird isn't weird in the slightest. A hundred different crawling things with no reason to be all slip and slide into each other and each unique creature becomes another hostile creature to be beaten or fled, little more. The weird.magical, and monstrous all need to be balanced by the mundane.