Fully agree, I think it would've been way better had they required a negative test and also every attendee to be fully vaccinated in order to participate. But whe'll see, maybe I'm too pessimistic.
As far as lateral flow tests are concerned as permission for certain events, here's something from Austria:
Austria is in lock-down-ish mode since basically last year November, with indoor dining closed and non-essential shopping only open sometimes.
The region Vorarlberg had relatively low incidence compared to the rest of the country at the beginnig of 2021, so the gouvernment decided to use it as a "model region" for opening indoor dining, with the requirement of a negative lateral flow test no older than two days or a PCR test no older than three days.
While the incidence in the rest of the country has decreased, the numbers in the model region have tripled.
Of course, our incompetend gouvernment calls this a success and is planning to implement the system in the rest of the country later in May as well

Of course the situation is not really comparable to the UK, as the UK has way better numbers now (incidence is a 6th or so compared to here) but I cannot imagine going indoor dining, even if they re-open, let alone attend a large-scale event.