I've not heard of Grenwich Waterfront Transit or East London Transit before, but the others are existing schemes.
It does seem odd that they have included Silverlink metro, but omitted the much more frequent Great Eastern stopping service to Shenfield. (I suspect this is more to do with where they have gaps in the map to fit them in).
Having included Silverlink Metro (presumably on the basis that it provides a userful service that interchanges with many other lines), they could have at least connected Waterloo, Vauxhall, Wimbledon and Clapham Jn by the same logic.
Perhaps the line to Watford Jn is included on the basis that it used to be part of LU? But that wouldn't make sense as that logic should mean the inclusion of places like West Drayton, and also what's happened to Moorgate to Finsbury Park?
Sadly the Metropolitan line isn't showing as going to Watford Jn so I guess that will never happen now.
This map is neither an Underground map nor a London Connections map, but it can't be called a 'frequent service map' either because it omits frequent lines and includes some infrequent lines. I'm not sure what it's meant to be :?
I think the purpose of the map is simply to highlight the changes to the network that will occur in preperation for the olympics. I presume the NLL is included as it will soon be truncated, with all services terminating at Stratford. However, I can't think why the Watford Junction locals have been included, while other important routes (as you say) haven't been included.
I would have said they'd have done better to upgrade the London connections map. However, it is no longer available from TfL, so I presume they no longer use it.