I don't think they are essential, but eating them in small amounts won't hurt. That said there are a lot of different nuts and seeds and some are easer to eat in there raw state then others. Nuts and seeds are for the plant to reproduce... Why would the plant/nature want us to eat them? I am currently in the process of slowly removing all nuts and seeds from my diet. Greens contain fatty acids in the right amounts. I does make me wonder why the 80/10/10 diet recommends 10% from fats, since this ain't doable for me without nuts and seeds, (more 90/5/5) but I don't have durians or avocado to available.
10 % calories from fat is a maximum value.
From the primal standpoint, humans are opportunistic and would likely eat these foods if available. If an ancient human or other great ape were to come across a squash and crack it open, they would have probably feasted on the seeds within. Have you ever seen fresh walnuts on a tree just as they are reaching maturity? You can crack open the shell with your bare hands and eat the nut meat inside.
From a practical standpoint, at least for women, 10% is a better ratio to achieve and maintain fertility. Dr. Graham has even recommended a little more than this if the woman is breastfeeding or pregnant (based on posts over on the vegsource raw page.)
The argument about "why would the plant/nature want s to eat them" only holds if you are an ethical fruitarian. However, greens are included in 80/10/10 and we eat them despite the fact that the plant doesn't want us to. I mean, it kills the plant and the plants produce certain acids to discourage consumption (ex: oxalic acid in spinach.)
I eat only 1 brazilnut a day (its high in Selenium which food is very lacking in these days) - just 1 nut gives over 100% of the RDA for selenium.
I also eat about 3tsp of ground flaxseed a day for the omega 3 fatty acid content, omega 3s are in plants too but just really tiny amounts. Chia, hemp and walnuts also contain omega 3 fatty acids.
All other nuts and seeds I do not really care for. My total fat content is usually around 5-7% of my total energy intake.