I think things like that stand out for me because of the strictness with which i was taught it in the past. I don't always speak or write with perfect grammar and in a casual environment it doesn't matter as much. I guess i feel that if you're putting yourself out there in the media, print, television, radio, whatever, in a professional circumstance, you should sound professional. These advert announcers all seem to be female too. Maybe they think it sounds cute? i dunno.