I think you took the "any questions/things to say" a bit too literally. It doesn't mean that it's appropriate to say absolutely anything. Surely you know there's a line? Would you say the following are appropriate?
"I just wanted to let everyone know that Dave and Lisa are having an affair"
"I just wanted to tell you that I hate this place and hearing you drone on makes me want to gouge my own eyes out"
Presuming the answer to the above is "no" then why not? Your boss said you can use the time to ask questions/say anything?
The reason you don't is because it's unprofessional and inappropriate. Presuming you understand that my extreme examples aren't appropriate, then what people are telling you is that what you said also crossed the line into unprofessionalism.
"Any questions?" means things like "would you like us to prioritise the task we just spoke about the the task we were assigned last week?" or "would you like the first draft emailing over or shall I wait until it's finished?" - Small, easy questions to finish off the meeting.
Things to say are things like "I just wanted to let everyone know that the printer on our floor is out of order so you won't be able to use it today but it will hopefully be fixed by the morning".
It's not an appropriate place to criticise your colleagues in public and throw them under the bus in front of everyone. That's something that's more appropriate to do in private. It comes across like you were trying to have a dig and get them in trouble in front of your bosses.