I think the point was more that Liara was supposed to be the easier chick to romance, though neither of them are really all that tough. However, when discussing Liara, they did seem to completely ignore the existence of Ashley, who was a counter to Liara's personality. Liara was the intelligent girl that is often shy and not always full of confidence, where as Ashley is the proud and strong female who is not afraid to speak her mind.
I think what should be noted about Mass Effect is that it really does do aliens well. Not every Asari acts the same. The Krogan on your team also does not act the same as the rest of his race, an ultimate goal of trying to unite his people instead of just accept defeat. Even some of the aliens that play minor roles all show different personalities. I forget their names, but the short guys with the masks are a great example. One will condemn you and your race because they are not yet members of the council, while another looks at you becoming the first human Spectre as hope that his race could also be accepted into the council one day. Being someone that has grown up with sci-fi and lots of bad D&D players, I'm used to non-human races all acting and believing the same, and any who doesn't is an outcast. This is a completely extreme and non-realistic idea, and I'm glad in what Bioware has done.
Also, as for the Asari, I think he is also looking at their race incorrectly. One of the things you keep hearing is that people assume that Asari are sex-craved sluts because of their personality. I've known plenty of people that make this same assumption about bisexual girls, and while I've also met plenty of bisexual girls that have proven this idea to be true, I've met some conservative ones that have completely taken me back. When you get right down to it, while there are plenty of people that believe there is no such thing as a "slut" anymore due to how openly promiscuous EVERYONE is at a young age, there are also a lot of false ideas about sexuality. If a girl likes to dress in a shirt with a low cut v-neck, it does not always mean she wants someone to walk up and grab her chest. It could easily mean "it's hot out today and I just need to wear something cool", or it could even mean "I just want to feel attractive today, so I'm going to show off my assets".
Again, talked to plenty of people where this is the case. It is possible to be a sexually conservative girl in this day and age and still show your boobs off, but a lot of people don't seem to really make that connection.
There's more I can say on the article, but I've rambled enough already.