The trouble with IC Cross-Country is it currently trying to be all things to all people.
In the BR days it was basically.
Newcastle - Birmingham - Bristol, some services via Leeds some Doncaster. About hourly
North West - Birmingham - Poole, some from Manchester, some from Scotland
Some of the North East services started from Scotland, some South West services went beyond Bristol. We even had services from Scotland - Manchester - Birmingham - Plymouth.
The core was basically hourly but most destinations were linked by at least one train per day. If you wanted to travel from Durham - Gloucester or Newcastle - Poole direct you picked that train.
The improvements to the core frequency were needed and probably the people that spend the most money are happy. The stops at Dronfield and Chester-Le-Street were forced on XC due to cuts imposed by the SRA (Dronfield for the removal of Northerns Chesterfield - Sheffield service and Chester-Le-Street for the removal of the Saltburn - Newcastle service via Darlington). Dronfield should go now it has the Nottingham - Leeds service and Chester-Le-Street should really be a TPE only stop hourly.
If you look North of Newcastle it is treated like the local service taking most of the stops at Morpeth and Dunbar, although these are not really stops that should be on ECML services that frequenly either.
I think the frequencies between Birmingham and Leeds / Newcastle / Reading and Bristol are needed. But they are catering for people making the local journeys and the seating arrangements of the voyagers don't suit it. A 3 car turbo has more seats and is probably better configured for Birmingham - Reading. Likewise Leeds is just over 2 hours away so may a 100mph class 444 style EMU is the way forward, the shops are going anyway but a lot of space is wasted on the voyager. Maybe run a Reading - Moor Street service via Dorrige with a 4 car 172 for the commutor traffic?
The big losers are the leisure traveller, Durham - Birmingham international forget going direct now. Linking long distance cities is gone and people now travel via London instead now they have to change at least once anyway. West of Plymouth we have less seats than we did under inter-city. I think most of the problems are really down to the Voyagers not been long enough, they only really matched the existing no of seats and not cover growth.
I don't think we can satisfy everyone with XC, it will never compete with air for the long distance flows so is speed that important? Can we ever get back to linking as many places together as possible even if it is only 1 train per day? Would a service such as Plymouth - Newcastle stopping at only Plymouth, Exeter, Bristol Temple Meads, Birmingham New Street, Derby, Sheffield, York and Newcastle be viable?
I think that it has lost what its original objective was to avoid London for people travelling long distance on direct trains, but it is filling in its new objective of linking Birmingham to other major cities. Shame the trains are too short! Another point is that Leeds - Edinburgh has a good market but the poor catering offer on XC still means many people will use TPE and East Coast rather than the direct train.