As'Salaam Alaaykum
You are right, there is indeed a big difference between maintenance and alteration..But the case of alteration isnt being talked about..
I know of cases with individuals with a nose which is slightly bent, due to this, they could not breath and a few other medical issues, so they had to get surgery performed, but if the person didnt have any problems, but changed the state of his nose for the sake of beautification, that would be classified as 'alteration'..which i believe is unnacceptable.
You are also correct, it doesnt matter to you what we or anyone thinks, what matters is what Allaah thinks, at the end of the day its the opinion of Allaah. Thats why we as muslims should refrain from posting up information which we have no knowledge of, or our own opinions or mis-interpret Qur'aanic ayahs. etc..