I started in 3rd as well, so my rose-colored glasses are there as well. I did like the fact that you could tailor things to stay cheap or get good, and man did I need this forum to tell me what did and didn't work, noob as I was back then (and still are).
It also sparked a lot of lively discussion on the forum.
While I think having the codex more streamlined isn't a bad thing per se, I think they've not hit the mark with balance between the various units since then. 4th was the age of godzilla lists (which I never liked), 5th was a meh codex where we couldn't even win battles against non-descript enemies in the fluff, and 6th was just a rehash of the same rules, basically, with some minor adjustments that did us more harm than good.
Should they hit the mark they set themselves for 6th (every unit equally viable, and on par with other codices) I don't think the streamline would be too bad. Though yes, it did take away a bit of nid flavor, I think there's more ways to get nid flavor in