If the MTOW were bigger from the beginning, the A380 would be even heavier. Seeing how Boeing built 747-400ER for just 6 orders, why not build A380-800ER for, say, 20 orders instead of making the baseline A380-800 heavier and losing 50 orders?

Remind me, did the ER 747 have a shorter fuselage to get the whole weight down? Did the 747SP have a shorter fuse too?
On the principle of same wing, same fuel capacity, less weight = more range (Unless fuel capacity was lost in belly tanks of the fuse…I have no idea on that)