Reasons are usually just newest kernel/mesa/etc. Most of the time the difference is very small, and often inconsequential. However, every now and again there is a major development that might make it worth it (IE: The graphics pipeline that all but made dxvk-async obsolete)
There hasn’t been a packaged release in a while. The repo updated last week, though. Not everything needs a high release cadence.
The most common alternative is probably Bottles