Just like a political speech writer do not invent what they write independently without some input and oversight by the politician, so does the commission.

This is also politics. You don't wait until last second to file a complaint. Politics is a slow moving process, not a single event, and creating support takes work over time. MEP are not subject experts so they will usually seek input long before it comes down to voting, which occur in parallel with the work of the commission.

"thanks, I can do nothing for now, but I'll keep that in mind if and when I have to vote on it"? is basically all that an citizens can expect by talking to a politician which only job is to vote on things. The same goes the other way around. If a politician today speaks about a political subject, I as a citizen can only say "thanks, I can do nothing for now, but I'll keep that in mind when its time to vote".