Are all cryptocurrency exchanges and financial lending institutions required by U.S. law to provide a 1099 form to the investor?

Would I fill the form on my own or just self-report the interest income on my taxes?

The lack of a 1099 doesn't relieve you of the obligation to report income. My bank isn't obligated to send me a 1099 if my interest is low, but I still have to report it. If a business claims expenses with a vendor of more than $600 they have to issue a 1099. If the amount is less than that the vendor still has to report the income.

According to the IRS Frequently Asked Questions on Virtual Currency Transactions:

Q41. If I engage in a transaction involving virtual currency but do not receive a payee statement or information return such as a Form W-2 or Form 1099, when must I report my income, gain, or loss on my Federal income tax return?

A41. You must report income, gain, or loss from all taxable transactions involving virtual currency on your Federal income tax return for the taxable year of the transaction, regardless of the amount or whether you receive a payee statement or information return.

Cryptocurrency platforms aren't regulated by the US government. That was the point of all these virtual currencies. They also claim that they don't have all the basis information to be able to properly report the cost basis. So it is likely that any 1099 you get will not include the cost basis information.

From the same FAQ:

Q45. What records do I need to maintain regarding my transactions in virtual currency?

A45. The Internal Revenue Code and regulations require taxpayers to maintain records that are sufficient to establish the positions taken on tax returns. You should therefore maintain, for example, records documenting receipts, sales, exchanges, or other dispositions of virtual currency and the fair market value of the virtual currency.