Granted, they're the most important prop of all, but they're still ultimately just props, and their level of importance depends on who's booking them. As it currently stands in WWE? Well, there are some people who really elevate a belt because they're really talented and charismatic (such as Miz whenever he holds the IC title, or recently with Becky Lynch and the SmackDown Women's championship). However, in general, it doesn't really matter who's holding what belt; we all know they'll take a backseat to whichever part-timer comes to town.
That's especially the case for the World Titles, as during the last decade and a half, the two brand splits and hot-shotting has made it so that every Tom, Dick, and Jack Swagger has had a run at some point. This practice started in the late '90s, but for most of the decade, WWE were very protective of their top belt.
The '90s saw a lot of changes, as Hulkamania died down and Vince McMahon attempted to reshape his company. He went through several experiments before finally settling on Stone Cold Steve Austin and Attitude.
But whether as a heel transitional champion, or as the top babyface, there were plenty of men who could have or should have been WWE Champion - but circumstances prevented them from getting the strap.