When I was growing up, my mom talked to me like I was an adult. Honestly, I think I'm a better person for it. I've tried to keep the tradition going with my kids and now that I'm a parent, because I think there are so many reasons why moms who talk to their kids like they're adults are amazing parents.
My mother was a single mom from the time I was a baby until she remarried when I was 9 years old. During that time I was so acclimated to her speaking to me like an adult, I would be completely flabbergasted (not to mention mildly offended) when other adults talked to me like I was a kid. In fact, there is this fantastic picture of me at about 5 years old sitting on my maternal grandmother's lap with a look of bewildered consternation on my face. She has the look adults get when they're speaking in "baby talk." My inability to tolerate these shenanigans may explain why we were never close.
When you think about it, if you took all the things you say to your kids on a regular basis and pretended you were saying it to another adult, you'd probably be pretty embarrassed. Hell, we all would. At least it might shed some light on some things we'd like to do differently. This is why I think parents who talk to their kids like they're adults on a consistent basis are amazing parents: