When asking for compensation, you should always have something in mind to purpose as a solution. See what the property offers for compensation (if anything), and then negotiate if needed.

With the restaurant closed, would you want to move to a different property? Do you want a nightly rate reduction? Do you want additional Marriott points as compensation? What is the primary inconvenience for you, additional cost incurred for breakfast and/or having to spend more time to get breakfast due to a lack of an on-premise option?

In any case, I think some compensation is appropriate due to the inconvenience and additional cost incurred for breakfast.

--Jon