Alternatives to Immortal Call / Trigger Attacks

I've yet to see a single build NOT use CWDT + Immortal Call (+ Increased Duration while we're at it). Some throw in another gem or two (golems, enfeeble, desecrate) into the CWDT mix, but Immortal Call is the big one.

Why are there no self-heals, AOE pushbacks (not that that'd work on bosses), or teleports that don't move you toward the enemy who just smacked you that are viable alternatives?

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Further, why can trigger gems only cast spells? Spells other than aforementioned golems and immortal call aren't going to be of any use on most attack builds.

Why not let Vengeance be a trigger gem itself that works with attack skill gems, for example?