Formal well defined methods work in formal well defined spaces.
Maybe "be aware of formal methods". Sure... Know of things. That's good. If a sitaution comes up and you think it relates, we can get more info. But getting in depth (if that's the suggestion) is... not something I think most developers need to do.
Let's see what the book is trying to say...
Formal... as in mathematical skills...
OK; I'm double no on this. NO NO!
And it says that knowing formal methods that are based in discrete mathematics are required for getting quality into the software... ... What?! No! NO! NO!!
Write a specification first... No.
OK; this is terrible. Like... maybe the source is advocating good things... Almost all of these principles are pulled out of a source. Probably one I'll have trouble getting. A lot of them are IEEE publications... and I don't have access to them.
Or it takes me a while to dig them up on the magical interweb... Anyway...
The formal methods the books is talking about have been abandoned by the industry. So.... No. We don't need, nor use them.