Personally I can't stand justified text - there are too many awkward spaces in the words just so it can fill a line. It is much better and easier on the eye to have standard spacing between words. When you get to the end of a row then your eye goes to the next row... It's not like we are running out and need to conserve pixels!
If the reader wants a different alignment then they can select it in their device/app. If their device/app can't override the publisher's default then the customer needs to a) get a better reader, or b) live with the default left justification.
To assume that everyone wants/prefers justified text is silly...IMHO
Now, if a customer specifically requests, or a publisher requires, a particular alignment then by all means you give it to them!
Cheers!