Are the armor active abilities worth a slot on your ability bar?

I wondered and listened to others on the subject before. With my experience, passives are good to have but seems like only best to get them when you can max them out in order to get the most out of them. Though some have mentioned, and is true just not sure if it's something you want or care about, that it's better at lower lvls to invest points into actual skills you can put on the bar so can lvl those skill lines you are most interested in faster. To each their own is really how it goes but if you want to lvl a skill tree faster, ignore passives for now.

from what i've seen/read, they are mostly useful for PvP

if you are playing as a tank I could see the use of immovable, but i think the other 2 are lackluster compared to other skills you can use for PvE

Evasion gives 20% dodge chance which can dodge AOEs and CCs. This can actually be a very useful skill since any ability that is dodged doesn't take stamina away while blocking.

Also one of the morphs, Shuffle, removes snares and prevents you from being snared briefly.

This is great in PVP and PVE because almost every enemy has a snare.

Both the heavy armor skill and evasion are great in pvp. If you are doing a 2h build, molten armor --> green dragon blood ---> evasion then critical charge and you'll be able to burst most people down. I've dodged up to 5 attacks in a row while bursting someone down. Same with the heavy armor skill (i forget the name) It makes you immune to nightbalde fears.

PVE is a different animal altogether, however.

The Light and Heavy skills are great, but I've never personally used the Medium.

As only a 25 Dragonknight, I am by no means an expert; nor can I speak to your particular issue as I focus on sword/shield and health. However, that being said, I will speak to my particular reliance on my heavy armor active skill. Though I am at work and away from my system at the moment so I cannot remember the exact name of the skill in question, I do know that I tend to rely on the Heavy Armor active skill in order to bolster my already existing sword/shield skills. For example, once this particular heavy armor skill is activated, for a solid 45-60 seconds (again, can't remember the specifics), it acts as almost a passive armor addition, reducing damage and allowing me to be a bit more liberal and aggressive while its active.

Basically my point is this; even though I can't speak for many here, I can surmise that you will get a lot of the same answers: find an active armor skill that fits your skills already slotted, as well as your playstyle and trait selections. If the armor skill in question, Evasion in this case, allows you to open up a situation that offers your other skills an advantage they otherwise wouldn't have, then I'd say it's quite useful. Try substituting it for a skill that you normally reserve for a "special occasion" or difficult enemy. You may find that the armor skill in question compliments your other slotted active skills and makes up for what you previously lacked. I would definitely give it a try, because it seems like a sizable people tend to overlook the benefits.

Just my two coppers.

Starting out you'll be better served by putting skill points into class and weapon abilities to get them leveled up to be morphable. And when you say "all over the place", that IS a good thing! Then as you start to get some spare SP, you can put pts into passives and morphs. There are plenty of SP, but early they can be a little sparse. I've heard that putting points into the skill line passives will help the skill line level faster, as they will act like a slotted ability when the XP is partitioned. To date, I've not touched any of the armor active abilities so I might not be a good judge of their usefulness other than to say I've never need them.

I think so. I use Harness Magicka in PVP.

I'm using the Heavy Armor active for dungeons, as I am a tank. Seems to help mitigate some damage, I chose the extended duration morph.

See http://www.esohead.com/skills/39197-unstoppable

Wondering how effective it will be if I stack it with

http://www.esohead.com/skills/22182-radiant-ward

But I am still a bit off from gaining access to that Templar ability.

For PvP they have their uses. For PvE not so much.
Heavy armor one is useful, but most classes can give the defense buff via their own skills and have a more useful side benefit.
Evasion is an interesting one, potentially it has use in PvE, but is far from a must have - none of my chars use it even in end game tanking. Its biggest use would be while soloing as it may help with survival, though in honesty I wouldn't bother with it.