Your content stinks
Gerry McGovern has a brilliant article on CMSWire that compares the common habit of migrating bad content into a new CMS to pouring sour milk into a different bottle. To quote:
Another team is assembled to take the old jug and migrate its contents into the new portal jug. Once all the putrefied milk has been drained into the new portal jug there’s high-fives and lattes all-round. Job well done, Joe! Project complete.
One of the first things that I talk to my clients about during a CMS selection is whether or not they need a new CMS in the first place. This year, I have talked three clients out of buying a new CMS. Sometimes it is just a matter of organizational neglect and bad content - and neither has anything to do with technology. Other times the CMS is difficult to use because the client made it that way by implementing onerous workflows and a bad content model. A simple upgrade and re-customization would fix those problems.
Another metaphor that I find effective is getting a new car when the ashtray is full but then emptying the contents of the old ashtray into the new car. But that doesn't have the visceral impact of rotting milk.