Even though I'm not involved in research of Bitcoin anymore because my work on Bitmessage takes almost all of my time, as a dedicated HODLer I feel it as my obligation to try to explain to the people interested in Bitcoin why the discord exists, and why it's pointless to spend time on it. I hope that it will help people deeply think about their own values, and use them productively instead.
The conflict is often explained as a governance problem. I think this while there is an element of truth in it, misses the point. The reason for the conflict isn't a lack of procedures, but an emphasis of the differences in values.
Main axis: conservative versus progressive
The main reason why there is discord is the conservative vs. progressive affinity of the members of each groups. The "Bitcoin Core" group tends to be more conservative whereas the "Bitcoin Unlimited" tends to be more progressive. For the purposes of this article, I'll differentiate betwen the groups by their reaction to obstacles with respect to the existing rules; when facing an obstacle, the conservatives delay changing the rules and try to find a solution within, while the progressives more readily embrace a rule change and consider it as a part of solution. Conservatives view the rules as containing a historic wisdom which may not be apparent. Progressives view them as contextual and as a reaction to contemporary phenomena.
These tendencies are a naturally occurring phenomenon and are largely influenced by psychology. They reflect themselves in all areas of life. People are unlikely to change their affinity. They associate themselves with people with similar affinities, and the community membership gives them a sense of belonging. If someone tries to treat obstacles in a way conflicting with their affinity, they will view it as an attack on their values, and follow by an immediate counter by any means available. Typical reactions are accusations of being a traitor (collaboration with the enemy), segregating their opinions (censorship), ridicule and other ad hominems. It happens in politics (Brexit, Trump), or in religion (the different branches of Christianity or Islam). Even in cases when there is some element of truth in the accusations, they are mainly a symptom rather than a cause of the problem.
Unfortunately, psychology tends to catch up even well educated, highly experienced and an otherwise reasonable people, and they go full retard. This causes an enormous waste of resources, which otherwise could be spent on productive endeavours. Perhaps millenia ago, in hunter / gatherer societies, such a reaction to conflict made more sense, as there may not have been enough time to discuss the allocation of resources rationally.
People in the Bitcoin community of all should acknowledge that some people are naturally more conservative and some more progressive. This would help to calm down the situation.
Secondary axis: collectivism versus individualism
A second characteristic, orthogonal to the conservative / progressive one, is an affinity towards collectivism versus individualsim. Collectivists want everyone to adhere to a broad set of rules, whereas individualists want just a very narrow set of rules for everyone. In the forking debate, collectivists want there to be only one Bitcoin and the other to either die or never start in the first place, whereas individualists are either indifferent or prefer that both survive. In the forking debate, collectivists point to lost network effect, consumer confusion and similar things. Individualists argue that a fork would prevent oppression and allow to refocus resources productively.
While this axis explains a smaller proportion of the debate, it is perhaps more important. You see, conservatives and progresives can get along, as long as they are individualists. Once they calm down, they will leave each other alone and try to resolve conflicts peacefully. But there is no such solution with collectivists. They will appeal to the higher good and demand your subjugation to it (i.e. them).
Next time you're reading, writing, listening or talking on the topic of the blocksize, try to see the arguments from the point of view of the two axes I outlined. You'll be surprised how much of the underlying implications can be explained by the affinities. Please recognise that the conservative/progressive split is more or less a given and both sides have a legitimate reason for their position, and therefore there is a legitimate potential for a conflict. Remember that the real danger is collectivism and its most encroaching manifestation, the state. If afterwards you still think that a common solution cannot be found, then calmly prepare for a fork, and spend your time and resources in your part of the community, in a productive way.