Hate to be the broken record, but this is consumer driven. Demand big bats at light weights and talk specs first, all else second and this is the result. Either accept smaller bats at full width are just as good, or get to the gym and use an Oz or two heavier so you get a bigger bat at full width. Or pay mega bucks for a 'low density' cleft. Or just work harder, get better in terms of skill level and apply yourself, then you'll score more runs. No bat is gonna do that for you.
As for talk of Pro's using 103mm bats. Of course there will be some using narrower bats, but they probably didn't realise they were at first. Can a lesser cricketer use them effectively with no issues? Of course they can. But if you expect a full width bat when buying one and get one which is 5mm or 6mm narrower without knowing, is that right? Not imo. That said, there's no law saying a bat has to be 108mm in width either.