From a letter- on wisdom and compassion, by Jason Espada

I just wanted to mention one thing you repeated in your short note- about what Goenka said about compassion developing naturally as a result of vipassana or insight- I think that, in all fairness, sometimes it happens like this, and sometimes not (otherwise all Arhats would be Bodhisattvas, and that's not yet the case). 

Actually, this 'wisdom leading to compassion' is the approach in the Zen tradition, as well as in the Theravada, and also, to some extent, it is the approach taken by the lineages in Tibetan Buddhism that emphasize wisdom practice more first, on the way to a full, complete realization. 

(Just a note here: The Tibetan word 'San-gye', 'Buddha', translates to 'completely purified- and fully developed', meaning that all faults have been removed (which is the cessation without remainder), and all positive qualities are brought forth, actualized.) 

So, to get back to my point- if it is so that sometimes liberation, the freedom of mind, leads to the full development of love and compassion, and sometimes not, then why not? Why does it sometimes happen and sometimes not? This is so important for us to consider as individuals, and so important for our world, really. 

And here's the best answer I can come up with so for- First, there are different temperaments, so that in any one system or approach one person will flourish fully, accomplishing all the different aspects of development, while another person may need other instruction, and to engage in other practices to achieve the same thing. 

Then, I've found the following teaching very useful to explain what is happening in any case. In the Tibetan tradition, they speak of 'the two obscurations' that keep us from seeing the truth of what is here. The first type is what they call the 'conceptual obscurations', or the 'obscurations of conceptual thought' (wrong views). These are corrected, or cleared away by samatha and vipassana- the quieting of the mind and cultivation of the strength of discernment- discriminating between the true and the false. 
The Theravada, Zen, and Tibetan traditions that practice non-conceptual meditation clear away this type of obscuration, the obscuration of conceptual thought, very effectively. 

But what happens, quite often as it turns out, - it's the characteristic possible sidetrack to this approach- is that the other type of obscuration, called 'the obscuration of afflictive emotions' (kilesa nivrana) is not always fully removed. Sometimes I've been calling these 'the qualitative obscurations'. And the all too common result is that people end up with a partial experience of the view of emptiness, or egolessness, one with the wrong concepts cleared away- but it is a cold, dark, meaningless, nihilistic experience, one that is lacking in the sense of worth, of the beauty and richness of what is here. 

The emotional obscurations are cleared away by the development of all he qualities that we associate with the good heart: the development of love and compassion, gentleness, patience, forgiveness, humility, honesty, gratitude, joy, generosity... These change the quality of the mind so that when the conceptual obscuration are removed as well, the experience is warm; the mind is bright, appreciative, and loving; and the feeling is one of richness, of the great value of life. 

See the enclosed pages on the Middle Way (from 'Like the Sound of a Bell...', towards the end- the last few pages). The no-self teachings of the Buddha are further expressed in the Prajnaparamita Sutras, and the Middle Way is a further explanation of those teachings. The term 'Middle Way' refers to 'being free of the two extremes', the extreme of eternalism (ego-grasping), and the extreme of nihilism. According to Middle Way philosophy, all the mistakes that people can have regarding the View fall into one of these two categories. 

Right View is accomplished by removing the two obscurations, conceptual and emotional, together with their seeds. So the development of love and the positive qualities of the heart are definitely an essential aspect of vipassana, or wisdom practice, seeing things fully as they actually are. Whether we arrive at this indirectly, or through our engaging in methods that directly cultivate both discernment and kindness, the need is there for everyone to have these elements present. That said, we should each practice what suits us best, and accomplishes a full result.