Platypus, thanks for your additional input. I hear you about changes being made in your courses without discussion. That is a frustrating situation, and we deal with it as well.
At my institution, there has been an effort over the past few years to ensure all the online courses have a similar look and feel. I can understand the value in that for the students. Banners are one of the requirements.
I worked on a different course redesign about 18 months ago, and the first banner that was created was not appropriate for the subject matter of the course. While it was superficially related to the topic, it contradicted the majority of the course content. I don't want to get into specifics, but it was an image that I felt uncomfortable promoting in rel@tionship to the course. At about the same time, the designer redid the course home page, and added colored backgrounds behind each item. By colored backgrounds, I mean multiple colors. There were green boxes, blue boxes, peach boxes, etc. all over the course home page. Many colored boxes. I'm in my 40s, and I found it distracting. The font color over the colored backgrounds (as ArtK mentioned above in his reply) did not provide enough contrast, and this problem also conflicted with some of the course content. In a nutshell, I wanted the course appearance to be a positive representation of the course material so it would serve as a model for students.
When I requested that the banner image be changed and that the colored backgrounds be deleted, I encountered resistance. Fixing a banner and removing the colored backgrounds takes more time. This was a frustration for the designer. If the designer was frustrated, then all I can say is that the frustration wouldn't occur if members of the team worked together on plans from the outset so that time would be spent productively.
I can understand a rule that all online courses must have a banner in order to make them homogeneous. That understanding falters a bit with the idea that all online courses can have just any banner so we can check the box and say that a banner was done. Really, there are some online history courses at my institution with glorious banners that do a beautiful job of visually communicating the topic of the course. I'm looking for the same kind of presentation for my course. If I'd had the opportunity to provide input, I would have told them that before they started the work.
My discomfort now is in telling the other two team members that the new banner does not communicate the course content in a meaningful way. I've received some good suggestions here, and I will follow them.