Why wasn’t de Havilland Hornet Griffon powered?

[Glider]

A Hornet with Griffons designed from the start to be a two seater (as it eventually became) could have had more or different uses but then it is a completely different plane in a different role.

A role such as a super Mosquito, but the UK had the sense to realise that the age of the jet had arrived and developed the Canberra

 

[GreenKnight121]

There are some reports that there was an early design decision to include a carrier-based version; those 1600 lb extra weight may have pushed it beyond the size that could fit on available RN carriers.

"Some reports"? Really?
The Hornet was designed with the possibility of naval service on carriers firmly in mind.

In mid-1946, the Hornet entered squadron service with 64 Squadron, based at RAF Horsham St. Faith.
Hornet F.1 Fighter version, 60 built.
Hornet PR.2 Photo-reconnaissance version, 5 built.
Hornet F.3 Fighter version, 132 built.
Hornet FR.4 Fighter-reconnaissance version, 12 built.
209 total land Hornets built.

On 1 June 1947, 801 Squadron was reformed to become the first squadron to operate the Sea Hornet, based at RNAS Ford.
Sea Hornet F.20 A navalised version for service on British aircraft carriers, 79 built.
Sea Hornet NF.21 Fleet Air Arm 2-seat night fighter powered by Merlin 133/134 engines, 72 built.
Sea Hornet PR.22 Photo-reconnaissance version, 23 built.
174 total Sea Hornets built.

So the Sea Hornet entered service 1 year after the land Hornet.