If you want a point-and-click interface to log searching I agree that some percentage of people like to start there (and I think splunk may even have that too), so I'm not opposed to it existing at all, but I feel very strongly that having the more sophisticated capabilities if you want to move beyond a point-click is a requirement.
To make it easier for myself, I think of spans also as structured logs with a schema that everyone had agreed on, which make it possible to trace requests across multiple services/clients. It's probably more than that, but I don't need academic precision to see how this is more useful during livesite investigations than simply querying logs with unaligned schemas.
- it highlights the intention of storing as much context as possible - it also hints on the implementation for a system that would serve them. One likely need to use columnar storage to store wide events, there is no way around it
But just a personal preference in the end.
Also IMO open-ended query language doesn't help in quick exploration, it's a barrier. UI and easiness of use is the paramount for adoption. To achieve arbitrary queries one can dump everything to smth like ClickHouse and query it with SQL. This would be a nice addition to any observability stack, to cover for a small percentage of the very deep explorations.