"""that the lack of easy access to items I carry was very detrimental"""
what do you need while you ride? all i need when i ride is on the handle bar bag, rain jacket, arm warmers, puff jacket, phone, battery charger, food .....
The handlebar bag I use on the touring bike (Ortlieb Ultimate 6) is too small for anything besides valuables, electronics, maps, and snacks.
This way it's easy to take it with me when I'm off the bike sight-seeing.
Rain gear, arm/leg warmers, warmer clothing all has to be stored elsewhere. The Carradice Nelson fit this purpose nicely, and is easy to deal with for food purchases for dinner on the way to camp.
What you describe as being carried in your front bag all fits in the Acorn front bag on my distance bike, but that's a different, lighter, and much faster vehicle with a mini-front rack to support the bag. The bag never gets removed from this bike as I use it for multi-day (and shorter) riding and never for real touring with sight-seeing stops.