Stack Exchange sites are unique in that all content is entirely editable by the community. Because of this, there is the temptation to make everyone sound chipper and cheery. You need to avoid this for a few reasons.
First of all, there was nothing wrong with Massimo's answer. It might not have been the wording that you would have chosen, but it wasn't offensive or condescending. It wasn't rude or incomplete.
Editing any content in a question or answer bumps that question to the front page. This is by design so that all users can have a "fresh look" at it in case the post was defaced or spammed. If every user edited every post that they came across so that it reads as if it were written in their own voice, there would be no original content on the front page - it would be a slew of edits.
Finally, it wasn't of considerable substance. Edits should address a significant error, typo, or omission in a post. Editing in links for citation where the source URL may have moved is good. Editing a command in a script where a user made an obvious typo in their answer is good. Editing an answer to capitalize a missed proper noun is bad. Editing to change the tone of a post that isn't rude or offensive is bad.
It's not that your edit doesn't make it sound nicer, so to speak, it's that it didn't add any value and an edit that doesn't add value just spams the front page. Don't take it personally, there are tons of rejected edits.