I have over 30 years experience from Electronics to Software Development and Testing and now currently in Software Quality (Processes and Software Technical Oversight).
This has been almost exclusively for Aviation and Space Satellite projects.
Elder Scrolls Online is a game, it is fun to play solo and also with friends.
In so much of the game there are no issues and it works very well - we should not forget that.
The impact of bugs for Aviation and Space Satellite projects can be critical and sometimes life threatening.
In a game the risk is purely limited to impact on the revenue generated and the satisfaction (and growth) of the player base.
In all businesses the resouces are limited for each project and this is correct.
The forum topics contain a lot of frustrations from players and I believe in many cases many of these could be dissipated through clearer communication from ZOS of what is to happening and when it is planned to happen.
One of the most useful communication methods I have come across is a published "Bugs Roadmap". This would associate reported bugs that are planned to be fixed with a particular weekly update/patch.
The list of reported but unassigned bugs does not need be visible but I suggest after initial assessment and a finding it is justified there is a time limit applied so it will be addressed within whatever you set as business goals. (example: In Satellite projects, 6 months is the goal but there can be issues still unresolved 18+months old).
With the expansion and development strategy to bring in new content and maintain interest of players there will always be many bugs in ESO and this is unlikely to change.
In the end the ZOS Software Quality Team are responsible for what we, as players recieve as well as being responsible for the improvement in quality of future deliveries.
Testing for game state driven technical issues is easily automated.
The visual and more complex group scenario testing is problematic as for instance with a group there are variables dependant on particular character builds as well as group dynamics. For any issues in this area relying on player "bug" feeback is the best solution.
Zos, you must know, the people who take time and effort to report bugs, comment in forums or contribute feedback in other ways Do Care about the game, what state it is in and where it is going towards.
Keep us supported and happy(ish)