It seems odd that people come up with such extreme ways of getting rid of a character they don't like. The writers may feel that Liara is important to the story and therefore they "force" you into recruiting her but if you don't particularly like her, then don't use her on your squad and don't bother talking to her. Liara is an important plot character and someone you would naturally consult regarding anything to do with the Protheans, and even the Reapers - remember she was the only person who initially believed that Shepard was telling the truth in ME1 because of her own research on the issue of vanishing civilisations. I prefer having her with me, as with ME1 and ME3, then sitting on the sidelines as in ME2.
Some romances ended up with more air time in ME3 than others. I romanced Ashley in ME1 but swapped to Jack in ME2. I got less air time with Jack in ME3 than I would have had I returned to Ashley but that was my choice. I still had my memory of that touching seen in ME2 with Jack to sustain me and know that behind all the bravado, there was a sensitive vulnerable person and that only Shepard had ever been privilaged to see that side of her. In another run through I might sacrifice Ashley on Virmire so I can get to react with Kaidan with a male Shepard, as this is partly influenced by my disappointment with the way Ashley was developed in ME3, but I wouldn't want someone else's love interest killed off deliberately because of this. As for Thane romance having less time in ME3, well you knew in ME2 that he was a dying man, he told you so. ME3 takes place 6 months later and Thane is much worse - it is heartbreaking but he had warned you. It is a pity they cut the romance related dying moments - if you've read them you'll know what I mean - but the "letter from beyond the grave" is still touching. Do you always have to have cabin scenes to make a relationship meaningful?
When I told Liara in ME1 that I wanted to be friends, I meant it. I didn't download the Shadow Broker DLC and hadn't read any of the comics but if she was doing all that behind the scenes, then I imagine Shepard appreciated it. As a friend, I was pleased to see her again in ME3 and know that she was someone I could totally rely on. When contrasted with Ashley, the thought did cross my mind that I had made the wrong call over the romance in ME1, but that was in the past and at least I could still value her as a friend without all the romantic baggage attached. I liked the shared memories scene on Priroity Earth (even if I didn't totally understand it) as a moment between friends appropriate to that character, just as my conversation with Garrus was. I certainly wouldn't want a character killed off just because some players don't like them. The Virmire sacrifice was hard enough.
So, OP, I agree with you, Liara deserves our respect but some people are hateful towards her because they think that's cool and badass - just ignore them.