See, even something as supposedly objective as this is going to run into problems. I'm all for the idea of consolidating a "recommended mods" list somewhere to refer to. The problem, as always, will come from what to recommend and who is recommending it. There's some mention of category heads and needing a certain number of people to "vote" something in. That's doomed to fail. The category experts are already likely to have one or more mods that would be appropriate fits within it, yet their opinion requires MORE validation than some random person who shows up out of nowhere JUST because they have their mods on the list? So yeah. If you're going to have category experts, you'll need to expect that these people will be recommending their own stuff, because chances are it belongs there precisely because they're the experts for that category.
As far as essentials, there is only one set of mods which is essential. The unofficial patches. Nothing else could be considered an objective requirement, which is why "recommend this" threads always get the same scatter-shot responses.
And I'll just repeat my standard mantra about wikis. I hate them. They're disorganized glops of crap in most cases. I've yet to see any that are navigable without knowing what you wanted to find ahead of time. Even the ones with awesome content waiting to be found are ALWAYS seriously lacking in proper link structure. I don't even begin to understand why the format got as popular as it is.