I agree with your original question - it is a stupid idea to leave the EU. For one thing we need the European Court to protect us from our own government.
Let me give you two examples though there are many more.
Air pollutionEach year about 40,000 people in the UK die an early death because of air pollution. The UK does not meet the UK's legal standard for air cleanliness.
What does the UK government do about it? Nothing. In fact the UK appeals every - it has appealed all three rulings so far - court ruling finding it is breaking the law. So much for "caring UK conservatism".
What does the EU do about it? The EU cares more for UK citizens than does the UK government and, fed up with years where the UK government broke its own laws and did nothing, earlier this year EU took the UK (and four other countries?) to court for failing to meet air cleanliness standards. So we are more likely to get clean air because of the EU than because of our own government.
Sewage on beachesRemember finding raw sewage on the beaches up to the early 1990s when only one beach in five met EU standards? What did the UK government do about it? Absolutely nothing. No - I apologise - that is not true. The UK government declared that Blackpool beach was not a popular bathing beach so pollution standards did not apply to it. That is hypocrisy - let's lie about it so we can ignore it. Who cares about those who actually use Blackpool beach - the UK government doesn't.
What did the EU do about it? The EU cares far more about its citizens than does the UK government. In 1993, fed up with years where the UK government broke its own laws and did nothing, the EU took the UK to court and the European Court ruled that the UK must clean its beaches. The result? No sewage on Blackpool beach. See The EU's effect on Blackpool's beaches – before and after pictures at
https://www.theguardian.com/environment/2016/oct/13/the-eus-effect-on-blackpools-beaches-before-and-after-pictures