The actual strength of the variety, I've found, is not in being able to throw out 6 different types of enemy in one encounter. It is the ability to have an entire Kobold warren, and have every single fight feel different and unique. Rather than just a bunch of identical kobolds over and over again.
Instead, the Compendium has 40 different options for Kobolds (well, probably 30 or so once you trim out repeats and named guys). Sure, you can have some basic minions in most fights to help the tribe feel consistent, but the ability for each fight to otherwise feature completely different guys in it? That's huge. And that's even before getting into other customizing you can do with templates or other modifications.
Similarly, I'm running a game right now dealing with a Primordial's army trying to conquer the Elemental Chaos. I need Archons, I got two-dozen to choose from. I need Giants, I have almost a hundred. Elementals? Tons. And even within any given sub-category (Iron Archons, Hill Giants, etc), there are usually at least 3-4 options to choose from, if not more.
So yeah, I'm very happy with the variety on hand and how much easier it makes my game.