There are two ways to ignore Middle Eastern realities, one is emotional, one is delusional:
Emotional is to believe that terms like 'international law', 'the international community', 'no recognition', or even the fact that a powerless, vulnerable, marginalised group persistently 'says no', actually mean something, or to believe that protesting in London, 'to show the British government that Israel's actions are not acceptable' will have any noticable effects. None of those things actually matter, but they're pretty much the only things people can cling on to in order to give themselves hope.
Delusional is to describe realities as delusions. It is delusional to describe the annexation of Area C by Israel as an 'Israeli fantasy'. It is delusional to think that 'the international community will not stand by and watch without doing anything'. Such statements have as much basis in reality as predictions of a Palestinian uprising that will see the the Jews leaving the Middle East.
1) International Law and Community:
Look at other breaches of international law and their consequences. Syria? Crimea? China? What did the international community do in response? Condemnation, withholding recognition, maybe a few fairly mild threats to impose pretty insignificant sanctions. Purely posturing, nothing more. And those are states we're not even very friendly with. What exactly could they seriously and realistically be expected to do about Israel? More than that? Rather less.
2) Lack of Recognition:
Changes what exactly? Certainly not facts. The international community may not recognise Israel's annexation of the Golan Heights, but that does nothing to change the factual reality. Similarly, if Israel were to formally annex Area C of the West Bank, it would be nothing more than just that, formal, as it very much is a reality already, and has been for some time.
3) Palestinian Rejectionism:
I very frequently hear people saying that 'the Palestinians say no' as though anyone significant actually cared. I frequently read about Mahmoud 'Abu Mazen' Abbas saying that he 'abolished' some proposal, for example the Greater Gaza plan that would extend Gazan territory into a part of the Sinai, and act as though that will have an effect, when all he's actually doing is giving Israeli hardliners a justification to perpetuate the current situation. And on top of that, more and more Arab states now choose to normalise relations with Israel and cooperate on security issues.
All in all, there are a lot of delusions surrounding the issue, but they're sure as fuck not Israeli ones. As can be clearly seen, instead of discouraging Israel, the international community emboldens Israeli hardline governments by setting precedents in allowing human rights breaches and militaristic expansionism to go unpunished and succeed elsewhere, perpetrated by states we're far from on the best of terms with. How anyone could believe that Israel is at risk of being stopped and held accountable by the international community is well beyond me. Kind of reminiscent of the threats that were once made against the US in fairly recent history, look what happened there, absolutely nothing, and it's not surprising.