1. Regarding the point of MDR, it is possible to levy MDR in Digital Rupee too. In Ethereum/Bitcoin too, we have to pay a transaction fee to transfer funds. Cause in the end, those networks are maintained by miners. In this case, RBI is maintaining the network.
2. Regarding the 2nd point, even Bank Accounts are secured through various Cryptographic Algorithms. They are basically compromised through social engineering/human errors, which is even possible in digital rupee. Even account based transactions are reversible.
3. I agree with this point. eRupee can be useful for transferring funds between large institutions. But I don't see much use of it in consumer space. Have a look at this article explaining the progress of Digital Yuan in Chinese Consumer Space:
While Beijing has made substantial progress over the past several years in developing a digital renminbi, it still faces many significant challenges preventing widespread use.
www.csis.org
It signifies that digital yuan is still facing difficulties in becoming popular among the general public.