Quite. Considering there's only generally 2 controllers on at any one time, to deal with the whole of England, Scotland and Wales, the work they do is great.
Could it be better? Absolutely, if there was another 10 people doing it, but even then, it wouldn't be perfect.
It's like the railway in some aspects, as the TOCs all want to do their own thing and NRE are trying to simplify things for those without railway knowledge.
Regarding your last point, again, it's set 'things' / reasons that used to be distributed via Tyrell (a messaging type system), but depending on the incident, sometimes a more vague reason would be used, e.g. for a SPAD or if someone has been struck by a train and they don't want rubber-neckers appearing.