Regardless of airline you have to realise that if LIS, MAD etc were potentially lucrative then airlines would operate them. Just because an airline decides to go where there is a strong market and where there is an incumbent doesn't automatically mean that the incumbent will pull off the route. There are countless routes where the newcomer, has grown the market or developed it's own niche. Besides, fostering monopolies isn't always the best for the consumer and I think we all realise that.
Now, from a supporter of an airports point of view I get where you are coming from. Of course you want to see new destinations but growing an airports network (as far as a vanity project goes) just isn't the airlines remit. As a business they have to follow the best returns and why should they take a hit on those returns (or even make a loss) just so you can see Madrid, Milan, Lisbon etc etc on your departure screens.
From an airport operators point of view, of course they want to grow their network so it is up to them to incentivise. Some airports provide incentive to new routes and often do their own research. Depending on that research they lobby the airlines. I'm not sure whether NCL has done this. If so, perhaps there just isn't a sizable market for Madrid, Milan or Lisbon??? I don't know.