I am also aware of the ability to share dashboards, however this has its limitations to needing to be a linked microsoft account to actually view it. It also only puts a link in an email. It doesnt put in any image or eye candy to bait the user into action. Another limitation I would like to overcome is to be able to programatically decide when I send an email to a user telling them to come look at something. So all in all, Sharing a dashboard or report does not help what I am trying to do.
Publish to web can eliminate that concern. Regarding getting a tile as a image, AFAIK there's no such a feature. There's already one idea submitted, You can vote it up. Check Provide PowerBI Graph as Image on request.
By the way, Power BI Tiles can be integrated with Office documents now, check this link. Maybe you could find a savior form the Microsoft Office SDK.