I used to have some morning glories grow up the hand railing on the front steps. They looked really neat when in full bloom. I think I put an end to them when I was ripping up some other vines. We'll see if they come back next year.
It's interesting that you call them a weed, and I can certainly see as a farmer what you mean. They're like mint in that once they take hold they don't like to give it up.
Yes, although they are very beautiful they can dominate and destroy all other plants. If you look closely at the last picture you'll see a loquat under the veil of morning glory, trying to find some light!