I'm happy to have Turin as a hotspot. Earlier this year, we actually used it as a base for a few days to visit the Palaces in Turin,
I am sure it is a great place to use as a "centre" (we too have used it) but we don't, for instance, have separate Hotspots for each of Liverpool. Manchester, Leeds and Sheffield - all of which could perfectly well operate as "Hotspot centres" for seeing the WHS of Northern UK/Southern Scotland . We have 1 Hotspot which is titled "Northern England". It currently says "Centre - Leeds or Sheffield". (could just as easily mention all 4 cities)
We could rename Milan to e.g NW Italy and list its potential centres as Milan, Turin....... Travellers can decide which centre suits them best.
If we start duplicating Hotspots a few kms away from each other but with virtually the same WHS within them where do we stop??
If we keep both we should add Ivrea to Milan as well - and I would still question the utility of including Portovenere etc in the Milan one.