I ask this in not a snide manner, but I can't help but notice in most cases DoTs are actually pretty weak and I wanted to bring it up before the skill balance pass is done. There are definitely some good ones- Crippling Grasp & Velocious Curse for example- but in many cases the DoTs don't do enough DPS, overall damage, can't be cast on multiple enemies, or are prohibitive in some other way (such as cast time). They're often just barely stronger than a comparable direct damage skill, and simply do not warrant taking up a slot on your skill bar.
I've always played DoT-casters in several past MMOs and typically the strength of these types of skills are that they do a rather large amount of damage in comparison to a nuke and can be placed on multiple enemies, but with the weakness of doing damage over a longer period of time (typically in excess of 10 or even 15 seconds) and are susceptible to removal via cleanse type spells. Obviously, ESO isn't beholden to the design of past MMOs, but it begs the question of several skills in the game that just don't have a place on a skill bar, and could potentially contribute a lot of attrition builds if they were in a better state.
If I might make a suggestion: Soul Trap would make an excellent skill to look into buffing for the purposes of providing everyone with a pure DoT- no other slows/cc/heals/frills needed. ~4x overall damage compared to a Funnel Health, 15 second duration, castable on multiple targets. Either rework one of the morphs or flat out buff the core spell. It would go a long way towards rounding out DoT builds that are quite frankly lacking at the moment.
Main: Breton Nightblade "Shadow Cleric" (Sustained Damage/offhealer) 5L/2H - Resto + S&B
Alt: Argonian Dragonknight (Stam DoTs/Tank) 5H/2M - S&B + Bow
Alt: Nord Templar Berserker (Rawr) 5M/2H - Dual Wield + Two Hander
Alt: Altmer Sorceror (Pewpew) 7L - Destro + Resto