Looks to me that aside from that, unofficially confirmed to exist, issue with Camera Roll app, the main cause of Other to grow is the following factors:
- How often you install/remove apps
- How often you update apps
- How often you add/remove new music
If you rarely do that, most likely you won't hit the problem.
For the time being, my only suggestion to avoid Other category bloating the space is to avoid updating apps or do that less frequently. It also seems to be quite reasonable to keep away from testing apps on your phone. So, make sure you install only what you need. Ah, I guess ya'll know the tune... The less you install on Windows, the less bloated it gets with time. Keep your app list clean and narrowed down to your must have apps, at hopingly the OS will run smooth.
Also, if you add/remove music frequently, it seems to affect Other as well. Might be covers used for background imaging are kept intact with removal of songs.
More to that, if your Other has grown flat out big, consider re-installing apps without re-setting phone device. Just do that:
1. Tap apps and remove them
2. Go to windowsphone.com and download the new XAPs from there.
3. [optional] Copy XAPs to your storage card.
4. Install the XAP anew.
That wouldn't save apps' settings if they were stored locally, but I am pretty sure, it'll cut you a slack for installing new apps.