Because you must justify your sponsors’ investments. Then you really must do it in a report-like fashion, showing it’s no bullshit, that your numbers, as compared to international standards (real ones) hold, etc., without making it boring as a corporate or academic report;
Because you want to attract more partners/sponsors and you need to showcase yourself;
You need to do it AFTER you actually have proof of such achievements. No promises.
You do it because you want your public to go on reading your stuff and consuming your products. In other words, you broadcast your achievements as a proof of authority: you’re not just theoretical blabber, you actually went there and got under the bar (and lifted a damn decent weight);
You want your students to take you seriously and do what you recommend, read what you suggest and adopt a critical attitude towards information. This is tricky: if you don’t do it right, you become another guru and you actually shoot yourself in the foot (unless you WANT to become another guru, in which case you are a despicable opportunist);
You DON’T want to broadcast yourself to be accepted or loved: you won’t be. You will be envied instead. If you’re not only successful, but also careless about the “nice games”, then get ready to be hated.