I also was totally unaware that scene on LotSB was not LI dependent. That was just wrong. It's right in the beginning of the boss fight. Shepard covers Liara while the second one gets covered by debris. If you romanced Miranda or Jacob or Thane, and brought them, they would be laying unconscious while you covered Liara. The writers shouldn't have played favorites there. Since this was Liara's mission she couldn't be knocked unconscious. So the way out of this one would have been to have no one get knocked out, and have Shepard move toward the LI, if any, and if no LI, toward neither. Basically everyone takes cover. The writers blew it. Since I only played this with a Liara LI, I didn't know this.
Quite honestly I think the Asari as a whole should have been written more like Aethyta, Aria, Enyala, Wasea, Vasir, Samara, and those commandos we ran into in ME1. Monogendered should have defaulted to androgyny in behavior with variation. I didn't mind Tevos and Irissa. I would have liked Liara to have been written more consistently and not shoved at everyone. If the perception is there it happened.
A lot of that could have been fixed by designating certain characters as not expendable in ME2: i.e. - Garrus, Tali, Miranda, Samara, Legion (no you cannot sell him to Cerberus), and Mordin. Okay now we've got the Turians, the Quarians, the Krogan, a potentially different Cerberus plot with Miranda instead of having it be about finding her sister, Samara because they wanted to show the monastery. But because everyone could die in 2, their roles were relatively minor.