I genuinely think there is a reason for why lucy does everything she does, let me explain:
First, the most obvious and talked about example: Her clothing. Lucy was raised on the belief that her body was a ‘prize’, something to only ever be shown to someone that ‘won’ her hand in marriage, this is why in earlier seasons of the show she gets visibly embarrassed, shy and shocked when more of her body is shown off to other people. I firmly believe that since lucy grew up wearing tight dresses and outfits that were incredibly modest, when she ran away and finally had the chance to be an individual she spent the majority of the year alone before she met natsu and happy trying to reinvent herself and figure out who she truly was as a person without somebody forcing their views and opinions upon her. I think lucys constant ‘little’ clothing is intentional, being used as a way for lucy to rebel against the ideology pushed upon her, she doesnt have to hide her body, she can show it off confidently without it being in a sexual manner.
Secondly, I think when lucy first joined fairy tail she had little to no social skills and therefore found it hard to fit in and conversate in a way that perfectly aligned with her true personality. Jude probably spent alot of time trying to push the loud, bubbly and ‘in your face’ personality that lucy had out of her to fit his idea of a perfect daughter, because of this lucy most likely spent alot of her life blanketing her true self and personality. This connects with my previous point, once she ran away she needed to figure out exactly what her true and authentic personality was without the meddling of an outside force, this could have easily been a reason as to why natsu originally found lucy to be annoying when she first joined the guild because she had yet to find who she truly was inside.
Finally, this is less so of a reason as to why lucy is the way she is and more of an explanation as to why i truly think lucy is the glue that holds most of the guild together. Let me explain.
In terms of natsu, in the first few episodes of the show its explained that prior to lucys arrival natsu was heading down a similar path to guild arts. He would take off on a long job searching for igneel, return, and immediately leave on another without much interaction with the rest of the guild. He loved the guild, of course, but outside of happy he didnt have a close bond with anybody within fairy tail(excluding lisanna), until lucy arrived. If not for lucy, natsu would have never developed his close bond with erza, or overcome his bickering with gray(even if only slightly), and he would have never outgrown his isolating behaviour. But natsu isnt the only one!
Lucy also has a positive influence on erza and how she decides to view herself as a woman, erza spent alot of time living in constant anxiety surrounding the tower of heaven and spent every waking second in her armour as a defensive mechanism for her fear, however after meeting lucy and spending so much time surrounded by a woman like her she grows to understand that she can appreciate her body, hair, and other features and use them to increase her overall strength and confidence. She also relies alot on lucy to be a ‘shoulder to cry on’, she admires lucys emotional intelligence and feels comfortable enough to take a step of her comfort zone to confide in her.
Lucy has also positively affected the guild as a whole and has changed many guild members lives for the better, e.g. gajeel and levy never meeting without lucys arrival therefore never allowing gajeel to understand that while yes, it is scary to love another it is always worth it, gray and juvia never meeting and juvia never helping gray overcome his emotional trauma surrounding his familys death and overwhelming hatred of deliorah, cana never finding the strength within herself to open herself up to the love from her father, and obviously the entire guild would have succombed to their fate during their battle against tartaros if not for lucys undetermined will. In addition to this, if not for lucy meeting natsu, happy, and fairy tail as a whole she might have never had the courage to forgive her father for her childhood and develop a meaningful relationship with him before his passing which while stung in the moment, definitely influenced lucys unrelenting forgiving behaviour and her constant push for second chances.