Yeah, there's a reason why I see that as one of the WORST developments of so-called "modern" D&D design...I don't see why one campaign should be regarded as better than lots of campaigns with different themes. Modern D&D's fast levelling doesn't particularly suit single decades long campaigns anyway.
Questions re the Red Hand of Doom campaigns (not at all familiar with the game system itself):I run open sandbox campaigns like Primeval Thule where players decide PC motivation, and narrower campaigns like Red Hand of Doom where players are asked to create PCs with a particular goal. The latter approach is not wrong.
"The particular goal" is the same for all PCs? Or each PC has to have a particular goal that may or may not agree with the goals of the other PCs?
Is the campaign open-ended, or more like a closed-ended AP? (closed-ended APs require much more buy-in by the players, including agreement to stick to the path)