I don't see how it wouldn't know I am finished. I am pressing enter, so that means I am finished and want to send the message.
When manually forming an emoticon, I type a ':' and then a 'P' to get ':P' with the 'P' still highlighted. When I press enter once, what I've typed changes to a
just like pressing space, except it doesn't add a space after it. When I press enter a second time, my message is sent.
I can deal with this double enter for emoticons, because I know I'm forming an emoticon, so I can train myself to do this quickly every time. Since AutoText is used for spellcheck and such, I won't always have the foresight to force it by pressing space at the end of every line of text I type, and it ends up being an annoyance.
Another thing I can point to is MemoPad, which does it correctly. When I type 'mypin' in MemoPad and press enter twice, I see the expanded version of my PIN. When I do the same thing in BB Messenger, it sends "Mypin".
All I'm saying is, some consistency would be nice and the current behavior is counterintuitive.