So, I checked what the status for the bug you mentioned, it seems to be because some services like MFE or Facebook don't allow sharing the contacts to third parties (yes, you don't have the right to share *your* contacts with yourself, that's smart). So I guess that for this reason the bluetooth daemon filters on "local" contacts only, I still don't understand why that would exclude contacts synced from bluetooth (which as far as I know are seen as local contacts)...
Anyway, it seems that the issue is being worked on, I can't promise anything regarding a fix since there is no solution yet, and it's not my team. Furthermore, I'm not totally sure what my NDA allows me to tell

About the ecosystem, you'll surely never reach the level of iOS or Android, I'm personally in this category of users that don't need millions of apps, but I can understand it's a blocker for some people.