As a Plat, you also have the 48 hr room guarantee, higher status for upgrades, arrival amenity (which can be more than just points). And some of the elite guarantees have more "teeth" in them if you are a Plat.

Also, depending on your stays next year, Marriott normally provides a "soft" landing when you don't make the nights for renewing your elite status. So next year you have less than 50 nights, if you are a Plat, you will drop to Gold. If you are Gold, you will drop to Silver. So you get an extra year of Plat/Gold benfits if you can achieve Plat this year.