Tender participation
Once your company is registered, you can participate in tenders.
Separate legal personality
A company’s existence is separate from its owners. This is so in the sense that a company will have its own rights and obligations i.e. it can incur liabilities, can have its own bank account, can be sued or it can sue in its own name.
To be professional
In fact, most corporates will not do business with unregistered companies. Once you are not registered, you become a bogus person. Even yourself you feel uncomfortable because it’s not legal to operate an unregistered business.  You remain small for quite a long time.
It’s important for continuity sake.
A registered business continues to exist even after the owner dies. Your business will be an asset that you can pass it on to the future generation. Look apple is still going on even after the death of Steve Jobs.
Access to credit.
Finance is the lifeblood of many small business, without it most small business fail. The major source of finance for small businesses is bank loans of which you need to have a registered company to access it. There are also Government programs earmarked to provide loans to small businesses. So there is a reason for you to register your company.