Currently my electronic cash balance represents a deposit at a commercial bank. On the other hand, when I hold physical cash, it is a direct obligation between the central bank and I. As mentioned in the article, 90% of cash balances are electronic money held at Commercia banks.
With a central bank issued e-krona, there is no role for commercial bank deposits, the e-krona is a direct obligation between the central bank and individuals/companies. This means that commercial banks have very different balance sheets to use for lending. It fundamentally changes the financial system and creates very different payment and lending opportunities.
Initially the central bank may only issue <10% as e-krona to avoid this impact, but it makes little sense not to follow through to making e-krona the only form of cash.