It's been seven years or so since I've been a TV reporter out in the field (and I don't miss it one bit), but here's my take on the question -
There are some newsrooms where handheld mics ("stick mics," as we called them) were used for everything, simply because that way the mic flag was in every shot - that, and a cheap stick mic (say, an EV 635, at $100 or so) is significantly less expensive than a good shotgun or lav (clip-on) mic.
At my newsroom, we had photographers who prided themselves on keeping their shots as clean as possible (and they had a shelf full of awards to back that up, I'd add.) That meant keeping the mic out of the frame whenever we could. Obviously, there's no choice when you're miking a news conference, but for almost anything else, the combination of a good wireless lav and a good wireless shotgun made the standard stick mic redundant.
It takes only a few seconds to clip a lav onto an interview subject, and once you get past the initial awkwardness of clipping it on, they tend to forget it's there, as opposed to having a mic stuck in their face throughout an interview. It also allows the photog a lot more flexibility in framing the interview subject, since the reporter doesn't have to be right in front of him/her holding up a mic.
My favorite mic, though, was the short shotgun - we used a Sennheiser MK-66. Great-sounding mic, very forgiving of bad placement, and even from three or four feet away, it sounded like a stick mic a few inches away from the subject. That was the go-to mic for impromptu interviews - you could walk up alongside someone, start talking with them, and never have the kind of "OK, we're starting the interview now" moment that tends to make people nervous.
I'd have to go back and look at my tapes, but my recollection is that we almost never did standups with the stick mic - I'd either put on a lav, if there was time, or just hold the shotgun out of camera frame and have my photog shoot fairly tight. (If it wasn't a very noisy location, sometimes he'd even hold the shotgun out as he shot...)