Yah, if the clouds are not overexposed with blue sky, colour would be nice.
But looking at the exposure on the ferriswheel (well exposed, not shillouette), I think the cloud is likely to be over....unless it was dark that day with shallow dynamic range.
BTW, I am just guessing. Please let me know if I am right.
Of course you are not obligated to shoot in colour, each has their preference and style. We were just thinking that if the sky is blue enough, it would be more appealing to our personal taste. Just sharing our tots.