I do it occasionally. Usually it's when I get in after a day of travel and don't want a big dinner (meaning heavy appetizers are enough). I wouldn't eat a full dinner size portion of the lounge food.
I have also done it in Asia several times where it's really a full dinner spread, often with larger plates, just because I needed a night in.
For some perspective though, it's almost never a choice between a hotel restaurant and lounge for me. The choice is always the lounge or going out to a restaurant. I generally dislike hotel food, whether from room service (the worst) or the restaurant (average food at high prices). If I'm hungry for a full meal, I want something good and perhaps with windows or an outside dining area, which isn't the case in most of the Marriotts I frequent for work (the non-resort kind).