Tbh I haven’t had a problem with a blank admin password, but bureaucrats do.
I’m aware that there is ETSI legislation that Mikrotik doesn’t (currently) meet https://www.etsi.org/deliver/etsi_ts/103700_103799/103701/01.01.01_60/ts_103701v010101p.pdf
https://wiki.mikrotik.com/wiki/Manual:First_time_startup
I haven’t deciphered the 134 pages of noise.
Just a heads up.
ETSI writes standards, they do not legislate. But i guess in this day and age you can identify as whatever you want.
There is EU regulation in the works to prevent usage of blank or default passwords.
As far as I understood UK is also going into that direction, funny they just left EU 
.
And IMHO it is a good thing.
The moment someone has access to your internal network, they can take control of all devices having such a blank or default password.
The usage of a common password for all different sorts of devices governing your network is in my view proof of bad admin practice.
Certainly with the existence of pretty solid password managers, some even free.
Convenience never takes precedence over security.
My view … feel free to disagree.
To add to @holvoetn …
I also think it is a good idea!
Especially for consumer oriented Network-Devices…
Don’t forget in some EU-Contries like Germany,
You are responsible for your Network and what appends on it
So if someone uses your Network for exemple to download illigal Music / Movies
YOU as the owner or the Network / ISP-Connection are liable.
A lot of innocent people had to pay fines of > 1500€
because of the 50$ Access-Point they bought online had a widely known SSID / Password
**(and because of a Neighbor using your WLAN for downloading Music)
EDITED Did not add anything constructive to the discussion