Virtually all the North/South passenger traffic would have been routed via the HS2 network as originally conceived, this would create more capacity on existing routes for freight serving a variety of destinations and terminals, it wouldn't achieve much to build a dedicated freight line and the costs of building a new railway are not much different whether its for 140 mph or 80 mph.
There would still be a time saving for someone who went say from Southend to Wolverhampton albeit not as great as between the hubs. But taking the very fast limited stop trains off say Birmingham to London Euston, would allow a service on existing journey times serving intermediate stations with the capacity created by shifting long distance trains to HS2.
I get your point on speed, but journey times do influence the mode of travel people use, an reduction in 30 mins to over an hour would mean that train would be more attractive than domestic air services, indeed France for example has reduced most domestic air services due to its high speed network, though it is of course a larger country. However, there are people who still use Manchester and Newcastle and of course Edinburgh/Glasgow to London air services so the time factor is an issue for them. If the city centre to city centre journey time is reduced to match the overall time it takes by air, taking into account the journey to and from the airport, then a shift becomes attractive to those for whom time is a factor.
I use Eurostar quite frequently these days and almost never fly to mainland Europe and the reduction in time that HS1 has created is the reason.
10 years ago I used to use train a lot to visit regional offices in all parts of the country, yes one can do work on the train as I did, but even so one spent a lot of time travelling for meetings. I remember when back in the day it was said that technology such as zoom etc. would mean business travel to meetings would die out both domestically and internationally. But though it has been reduced, it was still necessary to see the "whites of the eyes" of ones managers and indeed building relationships with clients requires some face to face contact on a regular basis. Given one is building a new line, it makes sense to make it high speed, but whether ultra high speed is necessary is questionable.