Possibly cheaper to produce the ported. Certainly the mass is lower, as is the magnet weight with smaller drivers. Cabinets also tend to be smaller. Ported is an easier design, I am lead to believe. Using one can get a lower in room response than sealed size for size. Certainly there are plenty on here to better go into the details of speaker design and placement than I. They don't make my Tannoy Eyris DCC either any more, that's a triple 6" sealed. 21Kg, almost 50lbs in weight, its a beast. Got that almost 15-20 years ago, no I idea what I would do without it. Everything comparable is twice the price.
All the other mixture of speakers I have, including the sub are ported.
As a general rule I would agree with Vader, bigger is better. However sound is about shifting air and consequently surface area is also important which was the point I was making. That said, there are a mountain of other factors which contribute to the overall speaker design and end result. There has been many an argument on here regarding ported vs sealed, particularly with subs.