I really dont see why you say that they are neccessary. Let me see..
NSS - useless, just a filler. needed for MSS
MSS- 4% extra threat. ok, but its about 1.3% threat every point... Blame NSS
HotW- yea, 100% needed. cant argue there
Perserverence- 6% reduced damage from spells... decent, but, not needed. there will be fights where the damage is physical, making this useless, and other fights where the magical damage isnt very high. Only on 10% of the total fights will this actually be noticable.
Now, let me see the other talents in the feral tree that we can possibly get.
KotJ - 15% threat boost over 10 secs, 1 min cd, take 10% extra damage for that duration. if used every time possible over a 5 min fight, it equals into maybe 2-3% total threat. plus maybe 4-5% extra damage taken. One could also dodge every attack during that 10 secs, negating the extra damage.
But, if we look just when its poped, thats 15% over 10 seconds. Suppose that youve been doing a good job, but a version of BL is popped, and the Arms/Fury warrior is starting to ride your threats ass. pop Enrage, start facerolling harder, and the warrior will probably not pull aggro.
Now, Primal Madness, 12 extra rage whenever Berserk or Enrage is popped. Possible useless if you are sitting at 80 rage when you use Enrage, or 100 when you hit berserk, but, with the threat normalization, its possible that one will be around 50 rage throughout the fight. Now, we go with the earlier hypothetical situatuation, Warrior during Bloodlust approaching you on threat. You start facerolling, at 50 rage. Enrage gives you 70 rage. Now, lets assume a loss of 10 rage every second due to spammage of abilities and Maul usage. after 7 seconds, you have to stop spamming maul. so, thats 1 Maul you couldnt use, plus low rage for the remaining 3 secs.. The warrior might not have pulled aggro, but, suppose he hit the 100 rage mark, and activated Inner Rage. He is arms, uses Deadly Calm. So, thats 50% extra damage (or 15%) during those 10 seconds. he pulls aggro, is eaten, and you lost a dps. You wipe due to the enrage.
Now, with Primal Madness, you can spam everything for 8 seconds. Now, you cant use Maul, but you have 1 extra sec where you can faceroll. the Chances of the War pulling is lower, but not by much.
Now, lets say you use Berserk AND Enrage. Mangle is being used every other button push, Lacerate is being stacked with Mangle Usage and you can get in an extra Maul, since it takes 9 secs for you to go to 0 rage. The Warrior didnt pull during Deadly calm, you keep a dps, boss is downed with 5 secs till enrage.
So, by skipping everything in Resto BUT HotW, and putting 5 points in KotJ/PM, you downed H Sinestra, and got Realm First kill! The 4% threat from MSS ISNT needed if you know what you are doing, BUT, the 15% extra damage from KotJ is a VERY good situational utility that CAN be needed. Perserverence is HIGHLY situational as well, and it possible will go unnoticed. I will admit that the 2 points in PM may not be needed, but, one can never know.
So, saying that all the resto talents are necessary, MANDATORY for a bear spec is wrong. I, myself, raid in a strange spec on live, and do perfectly fine without the present MSS, or even full points in Naturalist. 4% extra threat will go unnoticed if you are a good tank. 15%extra over 10 seconds, though, can be a raid saver when properly used.