Trends are peculiar in the sense that they sneak up on you. I don't remember when it was that I realized that mustard yellow was trending but it built momentum for many years before I realized it was a "thing"; I was having a conversation with my sister over the phone discussing her frustration at not finding a sweater online in the color "goldenrod", I knew the color she was describing and insisted she should search "mustard" instead, not to my surprise did she find many options in varying hues of gold and yellow.
The trend is for "mustard", it has taken over and dominated the world of decorating and accessorizing, it's not yellow and not goldenrod, it's very specifically mustard. In the case of this mustard yellow trend it's not just the color you're desiring, it's almost a lifestyle, add gray and you've taken it a step further.
Brand is important, if you are pushing a product or service or even just creating art, being vague won't raise your work above the noise of mediocre, you need to be bold and memorable, you need to be new and unique, push a new idea and become iconic.
This is branding, mustard yellow and gray are stamped on my generation like bell-bottoms on a hippie, it is defining, it is new (for now), it is current (for now). Enjoy it while it is here but remember it is a trend, so let it go when it is gone.