Regarding the mesh screen filters, I think it may be a good idea to keep them in assuming the risks have been considered by Subaru over these many years of having them be part of their design. Subaru like any other manufacturer would love to save cost and eliminate said filters if they could. This is just my guess, but because Turbo chargers generate so much heat the engine oil will have an increased tendency to develop deposits that are insoluble and large enough to destroy the bearings of the turbo if not somehow contained (or make it past the oil filter). Can you image what would happen if something like a very small piece of gravel were to flow into the turbo bearings as it spins past 10,000+ rpm? I know other car makers like Mazda, Mitsubishi, etc.. may not use these inline type of filters but I wonder if that is because of where the turbo is located within the engine bay. Subaru's turbo is pretty much located within feet of the passenger compartment. I wonder if the mesh screens are a safety measure to prevent exploding ball bearings from shooting through the firewall's thin sheet-metal and into the cabin if the worst case scenario where to happen.
The way I see it, if the engine were operating normally and maintained well then the screens should not clog as has been proven by so many people with 100k miles on their car. Perhaps this is one reason why Subaru recently lowered their oil change interval to 3,750 miles.