Nord is probably one of my top three favorite races in this game. Because of the way it is designed it is extremely versatile. Its also not a dirty milk-drinking elf too. :P I'm kidding of course, since I have at least one of each race. The thing about Nord that is so great is that it allows you to take on any role. Its obvious role of course is Tank, with the second highest health bonus, and a damage reduction that helps to soak up 6% of incoming damage. I would argue this damage reduction is better than having armor. On top of this you have a 30% health regeneration. I realize that health regen is not huge, but when you start stacking it with HoT's or health regen bonuses/enchantments it really starts to be noticeable, particularly on a tank build that utilizes shields or a shield. The big thing hurting the 'Nord Tank' build right now is that Tanks in general suck, particularly in the pvp arena. I think that's a separate issue though.

Nord healers are also fantastic because I find with healing that good enough is good enough. Any extra healing past a certain point is really a waste. Admittedly the more healing power is usually accompanied by more magic damage, but that's not the role of the healer, and the damage is secondary. The nice thing about a more tanky healer is that they can do their job longer without dying.

Nord DPS is a little more complicated, and where Nord really is at its weakest one might say. The thing is that a Nord still can do quite well with DPS. Without passives in magicka or stamina you might find you will want magicka/stamina return glyphs on your weapons, or invest in regeneration CP heavily, or drinks. I wouldn't consider the built-in tankiness of a Nord as a weakness though. The greater resiliency of the Nord means you can push more heavily into offense. I'm not saying this is the best role for a Nord, but I seriously doubt it is that bad, and I've seen some good Nord DPS (stamina and magicka). Admittedly they will shine better as PVP dps than as PVE dps, but that's because pve dps is a min-maxer paradise. In the realm of PVP you are building more toward the right combos, setups, and surviving long enough to kill more enemies. They both have different strategies and builds. To sum up: I think Nord is ok, and I think the real issue is that Tanking took a serious arrow in the knee with the last patch. I'm mad about it, but I'm also hopeful the developers will wake up some time soon and realize what a huge mistake they made.

Argonians and Khajiit on the other hand could use a little help I think.

Strangely, Argonians are currently best suited for tanking. The stat return on potion use is very helpful for replenishing stamina when you can't drop block, and the extra healing received stacks with the same buff from many other abilities/passives. Since high mitigation can be achieved through other means, this allows Argonians an emergency tool in their back packet that can't be replicated from other sources.

But back when Argonians and NBs shared an increased potion effectiveness passive (made potions effects 45% greater), they made for niche, but very powerful and flexible builds.

There have been literally dozens of threads about this issue, with tons of suggested fixes. Supposedly in the next update ZOS is rebalancing all abilities so we might see something changed then, but I'm not holding my breath.