For me, a major attraction of landscapes in general is the glorious interplay of colors, as well as any interesting aspects and forms in the composition.
I'd be very reluctant to remove the blueness of the sky and the rich greenness of the foliage, and so on. Howver, if the colors are rather dull and don't appear to match well, I can appreciate that a B&W conversion might be more appealing.
On the other hand, changing the color balance and saturation in Photoshop might still produce a more appealing result than a B&W conversion, at least for me.