One of the big problems is that certain sections of the press will just be hoping for you to fail, and will go over every word with a fine comb to look for something to moan and bitch about in the most bad-faith negative interpretation possible. Furthermore you need to be a renowned expert on any issue, cannot be seen to be thinking about something for more than a nanosecond, cannot hesitate in their answers, etc.

We are asking for too much of our politicians, so they will find ways to cope out of necessity, by limiting the exposure. We all like to think that we'd do better, but after being shafted by twats who call themselves journalists a few times we'd all be doing the same.