Sure getting a problem solved for oneself is nice, but what about the other users?
Opening a ticket in Arcanoae's Mantis will make sure the problem is being solved for you AND all the other users.
...as I will demonstrate on an example.
When I looked around for bugs and odd behaviour in ArcaOS, I found quite a few things (users of the testing mail list know my reports). As for instance Win-OS/2 had a problem that hard drives > 2 GB were seen as 0 Bytes free. - But only in Win-OS/2!
I've asked in forums how to solve this, and got a proprietary tool recommended, which needs to be loaded in Autoexec.bat. From that moment on, all the actual free hard drive was displayed nicely, ALSO in Win-OS/2's File Manager.
Knowing this, I did open a Mantis ticket at ArcaNoae. Recommended putting that functionality in from the start. - Outcome: Next release version had this functionality included. No user needs this proprietary software anymore, being loaded in Autoexec.bat. - Cool.

Without the ticket, others would still stumble over that bug, need to ask how to solve it (or find my post).
Of course I wouldn't be able to open such a ticket without the paid subscription. So infact I am paying to report their bugs. Weird, isn't it? But not only does membership help bringing OS/2 a bit further into our current time by paying the annual fee, but also actively helps solving problems for others too, by opening tickets and therefore bringing bugs to ArcaNoae's attention.