Other game on the same map may be also finished before anyone gets 3VPs, heh.
I guess the biggest thing to blame here is the system of counting VPs, instead of adding it every summer it should rather be 'controling VP province for x consecutive turns'. Combine it with 'no fort on VP' rule should make interesting game. I guess it cannot be modded though and would have to be done manually.
Next time on this map I'd rather use non cumulative VP, with something like 3 for the isle, 1 per gateway, 1 per capitol and an objective of 9 or 10 (the isle, all gateways, 2 or 3 capitols, or more caps and less special provinces), so even with the isle you can't stay in defence.