I believe that something has to give. Casuals have no need to have the same gear as raiders because...well they aren't raiders. I like the prospect of Fendred's idea and it could be implemented easily while simultaneously correcting the item level inflation.
Since we like having item level maximums in factors of 5 we can just do it that way. For example, Allagan Healer Grimoire (i95) is 71 magic damage. High Allagan Healer Grimiore (i115) is 77 magic damage . Crush this number down to i105 and all the current i100 will stay i100 but retain their magic damage numbers. Now for armour, current i100 can go down to i95 and i110 to i100. Every 10 item levels we have now should only be 5 but retain the same gain so i90 Argute Morterboard has 18 MND and 18 VIT, whereas i110 Daystar has 24 MND and 25 VIT. So i90 would remain the same, i95 Daystar would be 21/22, and i100 24/25.
This would all be in preparation for The Third Coil of Bahamut. So you'd have normal mode, and savage. Normal would drop i105 which is ~6 main stat/~7 VIT increase over High Allagan/Soldiery and Savage would drop i110 which would be ~14 main stat/~15VIT over High Allagan Soldiery. Obviously, Savage would be ridiculous in difficulty so that one doesn't simply get a massive stat increase. Also stated previously, have an extra boss at the end of Savage that would give something that normal mode has no way of obtaining without doing Savage.
I'd like to reiterate that casuals shouldn't complain about getting things that raiders have since they don't have the time, effort, skill, or all combined, to do the content that raiders do while putting forth the aforementioned categories in said content. If they (casuals) get their story mode and gear that wasn't completely worthless and allows them to do the next entry level iteration of raid, that should be good enough for them. Meanwhile raiders get the best of the best to show off (which is how it should be).