Do you know what's strange?

Then at times we may think we have overcome a lot of our attachment to certain perceptions, and we don't realise that meantime our aversion to others will have increased.

We have to let go of grasping and aversion in equal measures (and vice versa) in all situations, and I think at times too much emphasis is placed on only one or the other.

You make some interesting points.

With respect to why we grasp at perceptions; a return answer: what else do we have?
In normal life, it works perfectly: we feel hungry, we know how and where to get food, we eat it and the hunger is gone. In a zillion other ways, our perception of the world works quite good to get done what we want. What exactly is not true about the door we banged our head against, or the food we eat to still our hunger?
We have learned to cope with the world we perceive through our perceptions and labels we have given things - how else can we distinguish between pleasant and unpleasant things? How else can we do anything at all in this world?

In a sense, I suppose the whole thing with emptiness and selflessness is a purely philosophical issue. Really the only thing that makes it worthwhile to spend our time and energy on it is that we can not find ever-lasting peace and happiness in this world. But to cope with day-to-day life, I would think the illusory nature of things is pretty irrelevant. So much so that it is said that when one is in the realization of emptiness, at that moment, we are completely incapacitated in 'normal life': only a Buddha can perceive emptiness and conventional reality simultaneously.

To me it feels a bit like knowing that chocolate is not very healthy, but that does not really change its taste!
In my understanding, perception is probably the biggest obstacle to the realization of emptiness, as our perception continually appears to shout at us: 'I am a laptop', 'I am a table' etc.

We obviously need to work on more things then attachment; not just aversion, but all our negative emotions/delusions. However, as the Buddha taught, attachment really lies at the basis of all our misunderstanding of the world. The most harmful kind of attachment is attachment to the self: if we would not have that, all the other delusions would be easily overcome.
In a very similar way, when we realize emptiness, all our normal delusional ways of thinking and behavior become utterly silly and irrelevant, and only positive emotions like love and compassion make any sense, so with that enlightened wisdom and insight, it is relatively very easy to make dramatic changes to our thinking and behavior.

As I understand it, without having a direct realization of emptiness ourselves, we simply do not perceive the illusory nature of everything, so our 'normal' perception is our only measure of reality.

Well, I think it is a good question. I like what Rudy said. And I would add there are many basic principals we understand intellectually that are very hard to put into practice. And they all seem to come down to grapsing and aversion, but these are so basic they are in virtually every thought, emotion and sense perception. They are the basis of how we habitually reify the self.

It is pretty easy for me to see that giving success to and taking failure from others is essential to becoming a Buddha. But how well do I do it with others? Pretty darn poorly. Never the less, I find it a very good teaching to meditate on. And with years of practice, there are turning points, break throughs, moments where we get a little more relaxed and confident and real with ourselves and we see we can stop habitually over-looking or forgiving those attitudes in our selves and actually start to perform the antidote.

But for me those always come from meditating on the teaching or insight for a long while. It's not about making myself behave, but rather gradually developing the ability to do so. This is what practice is about.

As the third Karmapa, Rangjung Dorje, explains it in his "Treatise Distinguishing Consciousness from Wisdom," the seventh consciousness is immediate and afflicted. The affliction is the sense of self--I, me, mine--that arises in each moment.

We know that a dream is a dream unless we are within the dream and haven't yet developed the capacity to recognize it as such.

As I understand it, cultivating merit isn't necessarily about creating "good karma," but about transforming the limiting perceptions which arise with the sense of self. Everything we experience naturally falls into the ground consciousness, the eighth consciousness, which is our karmic conditioning. A lot of time and energy has gone into continually creating that ground, whether we think in terms of beginninglessness or merely within this lifetime alone. When you think about it that's a lot of investment for a vague, unknown result...perhaps something like relative comfort until death and then rest in peace.

Prostrating, offering, confessing, rejoicing in the merit of others, exhorting and beseeching the buddhas to remain and teach, all for the benefit of others, are means of using and employing the body, speech and mind for other-than self. Because the motivation for these is for the benefit of others, attachment to self, with its aversion, are reduced.

If attachment to I-me-mine is increased, so is aversion toward outer causes and conditions which might interfere, creating a kind of energetic feedback loop. Generally, the more it appears we have to lose, the greater our desire to keep it. I don't think we can work with one and not the other, as they like the two sides of the root of ignorance. For example, if I feel that I "have a lot to lose," that could be construed as either attachment or aversion.