That's fine if the text you're copying spells out the URL, but often it will be just a word(s) that are hyperlinked, so if pasted as plain text the software you

That's fine if the text you're copying spells out the URL, but often it will be just a word(s) that are hyperlinked, so if pasted as plain text the software you paste into has no idea there was a URL linked at all. (But I too wish plain text pasting was the default more often.)