The main problem is that there are limited number of users that really need large asset tracking solutions, and these big players have spent many years and now have something more or less working.
To surpass the existing systems, you really need to work on the actual production assets, and in the environment where hundreds of artists/programmers are updating it daily. Such large "practical" production assets are not easily accessible to startups or open-source projects.
I don't say it is impossible, though; AlienBrain seems to manage sustaining business. And I've seen few people who are truly happy with their asset management systems.
Sounds like an opportunity for a startup or at least a cool open source project ("make something people want")