I'm not sure the purpose of this thread is to completely reopen the debate on whether or not we should leave the EU, and most of us are probably quite fixed in our views on that anyway.
But to your question; -
- The EU is about further political integration. To be fair, it has never particularly tried to hide this, and it would have been known to anyone who took the time to look back in the early '70's when we chose to join (I wasn't old enough to vote then). UK style membership of the EU is now the exception rather than the rule: in theory at least all new members have to commit to joining the single currency at some point in the future. The UK isn't obligated to make such a commitment, but one result of that is that the EU will most likely gravitate towards being a two-tier organisation with those outside the Eurozone becoming increasingly marginalised. The Euro is the EUs main project precisely because it is seen as an irreversible step towards political integration. There is a very real danger that the UK would find itself having to pay to support this project even though it had no wish to be a part of it, and despite the fact that the existence of the Eurozone diminishes the UK's influence. It is therefore highly likely that we would in any case be faced eventually with a choice between leaving the EU and joining the Eurozone.
- In line with its objectives regarding integration, the EU is essentially a centrist organisation (i.e. decision making is concentrated at the centre). This is incompatible with the concept of independent nation states, and there have already been examples of the EU taking actions which conflict with the wishes of individual states (most obviously Greece). The Greek people did not give their assent to these actions, and indeed had voted in a government which had promised to do virtually the opposite of what the EU required (please note that this isn't a defence of Syriza policies, but rather a comment on the irrelevance of the democratic process to the EU). Large centrist organisations are not compatible with local democracy, particularly where there is such a divergence of interests across the member states. To make matters even worse, there seems to be very little opportunity for the populations of member states to exert influence over EU actions.