I will be. I'm a socialist, tending towards the radical. I recognise the economic arguments for staying in (pragmatically, because I am a socialist living in a world where most people want to be capitalist and I respect that) and genuinely believe leaving will create a degree of economic uncertainty and therefore hardship.
However, I believe the EU only functions in the legalistic consensus that came into being at the end of the Cold War - the idea that military power could be replaced by international law. We (the EU) relied on the law to police our borders and treaties to protect our interests. This was delusional - the power of the law was contingent on the military force of the United States and America's willingness to exert it to support the legalistic world order.
Once America discovered it's vulnerability to non-state actors acting beyond international law (terrorists) it ended it's support for the legalistic order in a big, obvious way - the invasion of Iraq. Without force the law is meaningless and the legalistic order is crumbling, with nations like China and Russia scrambling for military might to protect themselves. Smaller states are now gravitating to military centres of power rather than legalistic ones, and traders will rely on these centres of power to protect their interests.
The EU is both product and exemplar of the legalistic order: It cannot reform into a military bloc as it was created to cripple European militarism. The 'soft' power it exerted was only a shadow of American hard power and now the US has other concerns than supporting an organisation that's barely a trading partner and is a potential competitor (trying to regain American interest in European defence is, I suspect, the motivation behind TTIP and expansion into the Ukraine). As time progresses and the legalistic order collapses further the EU will cease to provide any diplomatic benefit and will instead become a vulnerable target; The manipulation of the immigration issue by Turkey is an example of it's increasing impotence. Social pressures from immigration and economic collapse will lead to enormous civil strife. I would not be surprised if, as continued members, we are forced to deploy the army to the continent in a canute like attempt to preserve the peace.
Continued membership will see us trapped into trying to support an organisation that has outlived the global climate in which it could persist; The best hope is to cut loose, accept diminishment of our global role (and attendant economic decline) and hope like hell that when conflict breaks out in Europe we are seen as a neutral, disinterested and pragmatic potential ally for whichever power blocs participate.