I'm not familiar with most Windows editors, but — at least on OS X — although blockwise selection is available in most editors, blockwise insertion like vim has is usually left out.

E.g., in vim say I have a list like this that I wanted to append a period to on each line (a simple example, but you can see its uses):

    foo
    bar
    baz

I would just type block-wise select it (<c-v>$jj) and then type A.<esc>

I use this feature all the time.

Wow, I had no idea you could bulk-insert that easily! Thanks for sharing

plus I still have to see a use for it. Usually I just go linewise or, inside a line, with movements like f) or $.

You can use it to block indent/unindent code, I find that quite useful.

It's mostly useful for ASCII diagrams, in conjunction with overwrite mode.

. . . or source code formatting, or adding comment characters to multiple lines, or in any other way making an identical change to several adjacent lines at the same time.