Importance of the first three Brahmaviharas in Theravadan Buddhism So while reading a lot of teachings, especially "higher" teachings, a great deal is mentioned about dispassion in worldy things, unattractiveness in the body and various contemplations on death. It's quite easy to get lost in these kind of contemplations without developing the Brahmaviharas to feel something positive (especially social positive emotions are important for humans).

I'm wondering if positivity is highly stressed in Buddhism? On the one hand the brahmaviharas are not withot reason called "the divine abidings". So I think one needs to dwell in them as much as possible. Also the last two points of Right Effort stress the importance of cultivating and maintaing positive emotions. On the other hand though, being non-delighted in things makes this look rather grim.

Maybe I haven't read much Suttas on Compassion, loving kindness, generosity etc..
Brahmavihara manifest naturally from non-defilement. Regardless, Brahmavihara is taught as a preliminary practise to Anapanasati. For example, from MN 62 and MN 118: 


  Develop the meditation of good will. For when you are developing the
  meditation of good will, ill-will will be abandoned.
  
  Develop the meditation of compassion. For when you are developing the
  meditation of compassion, cruelty will be abandoned.
  
  Develop the meditation of appreciation. For when you are developing
  the meditation of appreciation, resentment will be abandoned.
  
  Develop the meditation of equanimity. For when you are developing the
  meditation of equanimity, irritation will be abandoned.
  
  Develop the meditation of the unattractive. For when you are
  developing the meditation of the unattractive, passion will be
  abandoned.
  
  Develop the meditation of the perception of inconstancy. For when you
  are developing the meditation of the perception of inconstancy, the
  conceit 'I am' will be abandoned.
  
  Develop the meditation of mindfulness of in-&amp;-out breathing.
  Mindfulness of in-&amp;-out breathing, when developed &amp; pursued, is of
  great fruit, of great benefit.
  
  And how, Rahula, is mindfulness of in-&amp;-out breathing developed &amp;
  pursued so as to be of great fruit, of great benefit?
  
  There is the case where a monk, having gone to the wilderness, to the
  shade of a tree, or to an empty building, sits down folding his legs
  crosswise, holding his body erect, and setting mindfulness to the
  fore. Always mindful, he breathes in; mindful he breathes out.


It is reported that, for the Buddha, metta was very important. For example: 


  Monks, if for just the time of a finger-snap a monk produces a thought
  of loving kindness, develops it, gives attention to it, such a one is
  rightly called a monk. Not in vain does he meditate. He acts in
  accordance with the Master’s teaching, he follows his advice, and eats
  deservingly the country’s alms-food. How much more so if he cultivates
  it!
  
  AN 1:6.3–5