There are spells to render constructs and undead susceptible to sneak attacks, they should just add those.
As far as clickie damage goes, even though people complain (what else is new) about the manyshot timer mechanic, it works for DPS and gameplay. People don't feel annoyed, they feel incredibly powerful for 20 seconds. A 20 second burst actually has uses WRT bosses and big fights. A piddle of extra damage every 8 seconds has little use and just serves to annoy.
And to those who want always on extra damage against constructs, please take some Ranger levels.