Well, which is it - the DM is skilled enough to cope with creating descriptions on the fly or can't?
Cause the DM _needs_ the box text if they can't, but will very occasionally and rarely screw things up. And if they can cope on the fly, then they paraphrase the box text appropriately and cope.
Yeah, that seems like a mixed message to me.
Although the folks I've seen advocating buying adventures with nothing in them aren't folks I can agree with. If I'm buying the adventure, I want the work done for me. Otherwise I'll make up my own.