I was actually not thinking about an in-app voting feature, but some way of getting the communitys feedback on this, not just via an AmA but actually asking every HubSpot User to vote on a look and feel.
The more in think about the design, the more it feels like that there is just too little color on the right, therefore the design simply calls for a rather prominent color on the left, or else there would be not structure at all. The problem with that, is that prominent colors are often not accepted by the majority, which is why grey was the color every UI Design Team settled on it, because noone has an issue with grey. I feel like giving a little bit more color and structure opens up to the possibility to make the left a little bit less prominent.