[madebylaw]

Twitter is in trouble because a website with more features (photo albums, apps, blah blah) and a larger community has been consistently adding all of twitter's 'killer' features to their own site. Question: What's to stop facebook from adding public status updates or any other distinct twitter feature? Answer: nothing.

[gehant]

What's to stop facebook...

Their users - they expect privacy. Facebook, like its predecessors, is a walled garden.

[unalone]

Public status updates were already introduced.

[TrevorJ]

And blogs had 'more features' than Twitter too, but as they have proven, artificial constraints can make something popular. The minimalism is pretty much the point.