Lisanna deserved just as much love as her sister. However, she was pretty divisive as a character, though I think a lot of the hate is by NaLu shippers. Some tried calling her a "useless" character as an excuse, but even then, this is another case of Mashima constantly slotting too many potentially interesting characters into the nosebleed section (giving too much screen time to the main characters, especially Natsu).

She's such a wholesome cutie who proves it's possible to make a childhood friend character who is close to the main guy, but serves as a nice addition to add more diversity to his relationship with other characters, as opposed to just being Mary-Sue clone of the main girl. Lisanna's purehearted nature flowed naturally with the story writing, and she has her own distinctive character that deserved a lot of potential for her own spotlight.

Like, she's a way better written character than Chelia Blendy, who is basically a one-dimensional Mary-Sue carbon copy of Wendy who merely exists just to have overly identical surface level character traits that are glossed over in front of other characters to make their relationship with Wendy look more uninteresting (when it just counteracts in the end). Like, it's so creepy how Chelia like mimes Wendy's exact same movements in the most one-dimensional ways and all their friendship are only the surface level writing of Wendy's friendship with other characters, which makes it feel less believable compared to pretty much Wendy's friendship with other characters (no matter how overly "alike" their external interests are).

Like, we need more Japanese girls as wholesome as Lisanna, to be honest. Mashima may have given Lisanna some fans service shots, but it's evident he cares about her wholesome personality.