I think in context of other services this is fine, Durham isn't a major city. It wouldn't be one at all if it didn't have a cathedral.
Durham is an important city, both regionally and nationwide. The University means the city punches well above its weight economically. The University also means that the trains are well used.
But even in pure population terms it is an important stop, the city itself having a population of over 50,000. County Durham has a population of almost 900,000, although the southern half of the county would gravitate more towards Darlington as the railhead.
Seemingly this was the sort of thinking applied by someone unfamiliar with the reality of demand to/from Durham (as explained above) which resulted in withdrawal of the well used direct link.
We saw similar levels of bone-headedness when, in the early versions of VHF on the WCML, Lancaster lost quite a few of its station calls on the London expresses, since reinstated. Lancaster is a very similar city to Durham in terms of importance and demographics. Hopefully the shredding of the timetable at Durham will be revisited also.
The change was consulted, evidently there were not many representations suggestimg that the chanegd calling pattern would be a problem.
Or, as is more likely the case, those representations were disregarded in favour of the decision which was made. We saw how much weight the railway gave to representations made in places like Northumberland, Durham, and Nottinghamshire (i.e. none). I think the only effect that any of those representations made was the addition of one single LNER service in the morning peak from Darlington and Durham to Newcastle.
Any representations made by those in Stevenage would be even more easily disregarded because of GTR.
But the industry does love a pointless and largely unenforceable restriction.