The trouble with events

**This issue is meant as a long term placeholder for this issue, as I anticipate it will be with us in one form or another for the foreseeable future.**

Start here

- https://substrate.stackexchange.com/questions/4126/why-are-events-stored
- https://substrate.stackexchange.com/questions/4296/large-event-payloads-unsafe

So certainly having large event payloads, in particular when combined with big blocks, is not advisable. Problem is not solvable by dropping System module behavior, as that breaks lots of assumptions in downstream tooling, hence only remaining solution is to only have small fixed length event parameters, as initiated here: https://github.com/Joystream/joystream/issues/4135