The upshot is, vocal Wikimedians on mailing lists hate banners, and are quite willing to sternly lecture about their dire consequences! It's left to the Foundation, then, to choose between large numbers of donations from happy donors and unamused mailing list participants. Tough call.
My own opinion closely mirrors that of Michael Snow, so I'll quote what he said:
"That's not to say that I necessarily agree with all of the decisions that went into the current banners as to aesthetics or content. But I also don't have the expertise or all of the data that's behind those decisions, which is why I tend to reach a similar conclusion as Ziko. I trust that the fundraising team will attempt to balance all of these considerations, that they do listen to the concerns people have, and that they will make the best choices they can in light of the information available. Keeping that in mind usually helps me as I reflect on whether my own concerns are merely matters of personal taste or something more important."