Former colleagues of mine worked for the Norwich Union office in Sheffield and used to go for meetings in Norwich. As far as I could tell they preferred connecting at Doncaster and Peterborough to using the direct service. That may have been due to departure times, total journey times or price. I know I recently looked into a journey from Dore to Grantham and outbound was best on the direct service. Return was 3 trains but quicker, more options and cheaper.
With modern travel apps it's much easier to find the best journeys and prices. However we all like reliability. A good option on paper is no good if the trains frequently run very late, are cancelled or are so full it's hard to get aboard. Unfortunately that's not been a strength of the current service, for reasons that have been well rehearsed.