I think one of the problems with the TV-am watercolour ident was that it didn't really match the logo they used elsewhere as part of their on-screen identity.
The ident was inexplicably offset, yet the logo never was. It smacked of inconsistency.
As others have said, by the time their contract ended both the ident and the GMB titles looked very dated; although it's understandable that there was little enthusiasm for change by that time.
However, they did create a much better introduction for the news segments (later adapted to show the SKY graphic). Something like this would have performed better as an ident.
(Shown here at 1:00)