Years ago I went to a thinktank event on drone policy, and the congressmen they brought in spent 15 minutes saying that we needed to start discussing the important conversation of beginning to plan our policy creation dialog.
Many politicians over practice that. They need to have prepared talking points on everything. This often is different talking points on the same issue for different crowds: how you talk to religious fundamentalists about abortion is not how you talk to queer crowd - you will need to convince someone in one of the above crowds that despite one disagreement you are still worth voting for. Of course everything is impossible and you will offend someone (I used abortion as an example where you cannot win and so will want to skip), so it is tempting to avoid that: many politicians have plants who are asking a prepared question, always avoiding the hard issues while making a big deal about something small.
Politician sticks to his prepared talking points and riffs for fifteen minutes about something else.
Citizen feels disrespected.