This is an extremely valuable skill to learn as well as a difficult one. Unless you work in a vacuum this will help you work better as a team. It is one of the differences between a fantastic manager and a bad manager. People will value your opinion and it will help you learn more (because you will see more code and how others do things. Unless you're the best and do everything perfectly). It's also something you have to continually work at and improve upon. Of soft skills this is one I'd put in the forefront for any engineer.
But it's the impact that matters.
Good resources for understanding how to control the impact of your words include the book Difficult Conversations and others from the Harvard Negotiation Project.
The distinction between this and forms of communication often considered distasteful in technical circles is that you are - in fact - right (technical skill). It's not "sleazy" marketing if it really is "the world's best pizza!" :-)