The 'airport' concepts works up to a point if there is a large 'departure lounge' where travellers can wait in relative comfort until advised by comprehensive information systems to proceed to the platform just before their train is due. For many airports the final movement is via an enclosed tube and on one level anyway.
Stations suffer from two challenges - firstly when, like Sheffield, the concourse and waiting rooms are completely unheated (even when open, pre-COVID) and secondly because passengers need to spread out along platforms to be opposite a wide range of doors appropriate to reservation or class of travel, often beyond canopied areas, e.g. at Tamworth.
There is a further problem if the 'lounge' is at a different level but only served by one lift. The bottleneck dictates an early move for many passengers with buggies, luggage, etc. leading to more prolonged exposure to the elements.