Many people would argue that the financial industry is not regulated enough.
People were able to hack together exchanges for crypto-coins. The only thing that stands in the way of doing this for private stock/tiny companies is excessive regulation.
Crypto exchanges are examples of how to create a financial system that lacks security (both the technical and financial kinds) and trust. It's an example of how NOT to do things. Crypto exchanges act as broker, exchange, clearinghouse, depository and trustee. And do none of these very well.
In the regulated world, exchanges do not hold your assets. There is nothing "on deposit". Your broker (who holds your cash assets instead) is insured. Brokers don't even typically hold your securities, they just track your positions. The security assets themselves are held at depository institutions. Etc, etc. This system is not by accident. It was developed through a long history of trial and error to minimize the impact of fraud, abuse, bankruptcies, etc.
I'll be the first to recognize that most financial regulators have been very slow to adopt to the crypto world. That's because so many crypto tokens are either not securities or quasi securities and thus defy easy classification. Thus some old rules don't really apply well. They're also paranoid about money laundering, which doesn't help.
The software aspects of setting up exchanges are challenging but ultimately not the hard part. I guess my point is that just because something is easy to do doesn't mean it should be done.