As long as you have in writing that the card will be the exact...

As long as you have in writing that the card will be the exact same other than the additional extras you are going to receive there should be no catch. But like someone else has said it pays to check both fine prints. Probably the system flagged you that as you do constantly spend over a certain amount ($1000) each month you might be entitled to have an increase CC limit if you have a platinum card, but not the basic card you have now? I do know each tier type of card you have only has a certain limit.

We got a platinum card with our mortgage that comes with all the bells and whistles you are being offered. It started off at $5,000 limit, but within 6 months they sent us a request for 10G, so I took it. We had a few big expenses coming up and well better to have the money in the offset account for a further X amount of days then taking it right then and there. About 1 yr after that a new limit increase to $20G. Umm'd and arr'd over that and only asked for $15G. Every 6 months we get invited to the max limit of $30G, but I always decline. $15G is more than enough for us, most times our CC is about 1,500 - 2,200 just depending on what happens in the month. If you happen need to spend more than 15G in a month you could also just add money to the CC before you purchase, as long as you don't go over the limit it will always be approved.

Like you we pay off the full amount on the due date, you might think that your card issuer does not receive any money from you but they get a small % of the total transaction(s) you make on the card, the interest from people that do not pay are just cream on the top for them though.