Some brands already seem to be getting the balance right. A bot needs to capture a user's attention quickly and display a healthy curiosity about their new acquaintance, but too much curiosity can easily push them into creepy territory and turn people off. They have to display more than a basic knowledge of human conversational patterns, but they can't claim to be an actual human -- again, let's keep things from getting too creepy here.
The upcoming TODA agents are good at one thing, and one thing only. As Facebook found out with the ambitious Project M, building general personal assistants that can help users in multiple tasks (cross-domain agents) is hard. Think awfully hard. Beyond the obvious increase in scope, knowledge, and vocabulary, there is no built-in data generator that feeds the hungry learning machine (sans an unlikely concerted effort to aggregate the data silos from multiple businesses). The jury is out whether the army of human agents that Project M employs can scale, even with Facebook’s kind of resources. In addition, cross-domain agents will probably need major advances in areas such as domain adaptation, transfer learning, dialog planning and management, reinforcement/apprenticeship learning, automatic dialog evaluation, etc.