Uckfield to Lewes is a ridiculously over complicated journey by train nowadays.Exactly. There are far too many gaps in the network as it is.
I disagree with the premise.
Sussex, for example has been left with a wholly inadequate passenger network that lacks resilience at times of perturbation, primarily because of the hawkish obsession wil line closures pushed by Beeching from the Stedeford Committee onwards, and continued through to the 1970's.
The real failures of that era need to be digested and understood to avoid repetition.
I also disagree with the premise of pruning the passenger network. In a developed society like Britain in a geographically confined land area, there are unlikely to be large scale population abandonments (at least until climate change makes large areas uninhabitable), so its unlikely that there will be a justification for pruning.
East Grinstead, coming from the West, south, or east is now more difficult. West to east, thanks to the removal of the high level line that ran from Three Bridges to Royal Tunbridge Wells.
The Beeching cuts did make some relatively simple journeys more complicated to do, and expensive, by having to travel the extra miles to complete.