I agree with others - the functionality to be able to add (or at least link) attachments to other people calendar invites needs to be a priority ...I have the situation where a fellow Finance colleague has set up a meeting for us and others. I then need to attach a spreadsheet for all members of the meeting to use. Since I cannot attach a file to the calendar meeting I need to send a separate email to all the stakeholders which is much more hassle for everyone as when its comes to the meeting they need to remember when my separate email was sent :-/
As for your suggesting of replying to the person who set the meeting up .. well they are off on annual leave so that is not use!
The work arounds suggested are no use either since I d not have access as an IT administrator
Microsoft should be working with the people who use the product daily - not being against those people!!