[PinkMilkshake]

That might be specific to where you are from. I can only speak for Australia and New Zealand, but "Hi" is perfectly acceptable. Unnecessarily formal speech can come across as disingenuous, and maybe a little patronizing. Although the same is true for overly familiar speech as well.

[checkyoursudo]

I say hi in Germany all the time, which even has a formal form of interpersonal communication, and I never even get a second look from anyone. I say hi or hej on purpose because I am trying to teach Germans to be more efficient (some say moin, which is decent). If hi is fine here, then it is certainly fine in any English-speaking country/company. :)

[LAC-Tech]

New Zealand doesn't have formality. People don't even wear shoes.

I realise I'm supposed to think it's charming but it's always made me cringe.