I love the dark take on Troi in this thread 
Seriously, though, even the writers struggled with her character in the beginning. It's why Troi is underutilized in the first season or two. They figured that if she can just read everyone's mind (or sense their feelings/intentions), where's the drama? You may remember in "Encounter at Farpoint" she communicated telepathically with Riker. That wasn't done again, with Troi only receiving telepathic communications in later episodes (including from her, full-Betazoid, mother).
More background on how the character was developed here.

Seriously, though, even the writers struggled with her character in the beginning. It's why Troi is underutilized in the first season or two. They figured that if she can just read everyone's mind (or sense their feelings/intentions), where's the drama? You may remember in "Encounter at Farpoint" she communicated telepathically with Riker. That wasn't done again, with Troi only receiving telepathic communications in later episodes (including from her, full-Betazoid, mother).
More background on how the character was developed here.