Yes it would be nice to have a like or thanks button, but this forum software was written well before the rise of social media, so nobody thought or cared about it.
Adding own extensions to an existing software might break your ability to update so it is best to leave it as it is and customize only the things the coders left. Newer versions might have it (or not) so the post from algae already says most of what can be said.
In short - don't mess with the code
Jo