Different Links, Different Goals
You need some types of links to have enough raw PageRank to keep most of your pages indexed, and to have your deeper pages included in the final selection set of long tail search results. You need links from trusted related sites in order to get a boost in result re-ranking.
There are also a few other types of links to look at, if you wanted to take a more holistic view:
- links from general trusted seed sites
- links that drive sales
- links that lead to additional trusted links
- links that gain you mindshare or subscribers
Some of those other links may not even be traditional links, but may come from a well placed ad buy.
Every unbranded site is heavily unbalanced in their link profile. If you do not have a strong brand then the key people in your community who should be talking about you are not (and thus you are lacking those links).
Most branded sites do not create enough content or do enough keyword research to fully leverage their brand strength, but occasionally you see some of them get a bit too aggressive.