Credit Cards and their charges

We have a "fee free" Coles credit card issued by Citigroup with a $3000 limit. It has been held since the Coles Myer days (different issuer back then I think) and because I pay the entire balance before the due date each month we have something very rare in this world, a useful service for no direct outlay. Sometimes an online merchant adds a 2% credit card fee but most of the time if there are any charges we don't see them.

Now Coles is offering us a Platinum Card because we spend over $1000 per month. They guarantee that all fees and charges will remain the same but we will be given free insurance for purchased items if they are lost, stolen or accidently damaged. That could be handy. Coles is also offering a free Concierge service to platinum card holders, I doubt if I will use that but you never know.

Now where is the catch. There is an option to decline the Platinum card but if Coles wants to offer us another free service for no direct outlay why should I say no. If they really wanted to cancel or alter our fee free card because they make no money from me, Coles could have done that at any time in the last 20 years.

Does anyone have experience with being upgraded to a platinum card from any issuer. Is there something they don't tell you about that is good or bad about the process. The card number changes so I have a couple of direct debits that will need to be updated but I can handle that. I just remain slightly suspicious of Coles motives for offering us something extra for no charge.