If you fail to do so, the issue/s which had you make change might not be solved. Furthermore you might run into [[System_Maintenance|''partial-updated'']] scenario which can cause havoc in your system. For more detailed information on how pacman works you can read up on the [https://wiki.archlinux.org/index.php/System_maintenance Archlinux Wiki]
如果你不这样做，让你做出改变的问题可能不会得到解决。此外，你可能会遇到partial-updated的情况，这可能会对你的系统造成破坏。关于pacman如何工作的更多详细信息，你可以在Archlinux Wiki上阅读。