Not everyone is young and fit enough to walk half a mile, or to change stations with suitcases etc.
Why would you be walking though? For a start if you're travelling from Southport to Hereford as you've mentioned there's no actual need to travel via Manchester at all.
For journeys where via Manchester is a logical option, there are 2 train services per hour and a frequent Metrolink tram service linking the stations. Changing trains at Salford Crescent is also possible. I just don't see where the point about a requirement to be walking comes from.
As for changing on my way to Hereford, Crewe is a gamble if you want a seat, Chester is going the same way, which is why I much prefer to board at the start of the route i.e. Piccadilly
So, for clarity, the most compelling reason to re-write a timetable that we have come up with is that you dislike joining a train en route after it has departed from its origin station.
I still say Victoria is in the wrong place for easy access to the main retail/eating areas of the city.
It's interesting then that passengers from the Huddersfield line were outraged at the loss of their through services to Manchester Victoria, which were replaced with ones to Manchester Piccadilly instead, because they were so much less convenient for the main shopping area of the city centre.
There are lots of complaints, both here and elsewhere, that Manchester Piccadilly station is poorly located, a long walk away from the main shopping street on Market Street.
Another thing is that Virgin only operate out of Piccadilly, to the best of my knowledge.
I just don't see how this has any relevance. Next to nobody would be travelling from Southport to London via Manchester...