It is also down to the fact the a lot of the LCCs carry passengers who are on board to get away for a few days (regardless, to an extent, of destination) rather than having to go to a specific place.
Such passengers are generally expecting to pay roughly the same whether they fly 1 hour or 4.
I do think there is scope for a long-haul carrier to destinations within 8 hours (allowing 1 aircraft operation and a daily service) concentrating on a premium-economy and business product but on a low cost basis.