I read on one of the blogs "why do they keep going on those dumb trips?" Well there could be many reasons. Take away the TLC part and the TV show--that part is a given.
1) Let's get the kids out of the house and show them the world still exists for them and that their life isn't really ALWAYS just focused on baby sister Josie, sometimes they are important too
2) They do live in an interesting part of the country and it's nice to be able to explore it since they have an opportunity
3) Why should they be locked up in their rental house for the duration--tv show or no tv show?
There were complaints that the girls had to come along. Why don't we see the girls doing things that are age-appropriate. Or why do the girls have to come along all the time--is that a requirement. Here's my guess. I have a feeling that the girls have plenty of time to themselves when they get to do stuff all their own and that's exactly how they want it--all on their own. And that part isn't filmed. My feeling is that Jim Bob and Michelle have set up a life that is one part TV and one part PRIVATE...so when they are on field trips it's TV life time.
I haven't seen the episode yet, and won't until TLC posts it. But the blog I read had posts from mostly those who disliked it and for usual reasons, the girls were taking care of the children, not Michelle. The girls weren't enjoying themselves and looked bored--why did they have to come if they didn't want to? To quote other posters--they are teens and that's how teens that age always are, even the mild-mannered Duggars.