I try and go cashless as much as possible. Buying stuff from the Internet, unfortunately, requires at least a debit card which is as close to cash as you can get.
Buying with cash is also anonymous. Except for the security cameras :)
Regarding the possibility of e-money: I reckon the difference in interest rates between cash and e-money will not be big enough average Joes really worry about.
If you had millions in cash it might make a difference. But for average Joes like me, doubt it.