To blend the two ideas, you can use the same 'meals' but change up specific ingredients, which can help simplify but also keep variety in your diet.
For example, if you have a sandwich and fruit every day, switch between turkey, beef, tuna (etc) for the filling, and switch between banana, apple, pear, etc.
If you want to make a pot roast, use different vegetables. Instead of just potatoes, carrots, and onions, try beets, turnips, parsnips, celery, mushrooms, etc.
I agree, it can really help to just know what you'll be eating every day without having to plan out meals in advance, but if you ensure variety even within your 'same' meals that can help ensure a fuller range of proper nutrition.
Pros: 1) It's simple. 2) Easy to budget and manage, financially.
Cons: 1) Like JERF said, your body needs the spectrum of vitamins and minerals on a regular basis that come in food, and chances are pretty good that you'll fall short in some areas if you don't mix it up. Vitamin supplements are not necessarily a great solution; the absorption of nutrients from food is great, whereas absorption from pills can be minimal to nill. 2) Goodness, that would get boring fast! I get sick of most foods if I eat it twice in one week, much less every day until the end of time. 3) This should ideally be looked at as a lifestyle change, not just a temporary fix to take some pounds off. Think about it - you put some unwanted pounds on doing what you do everyday. If you just eat the same things for the sole purpose of taking weight off, then return to old habits, what is going to happen? The pounds will probably come back, and often faster or in more abundance than the first time. That's the pinch of yo-yo dieting. Do you plan on eating just those same meals every day for the rest of your life? After a few weeks, I don't think I'd ever be able to look at those foods again.
What most of us do is to put a few staple meals in the rotation, the change it up for the rest. I have some meals I eat once a week, every week. No matter what else is on the grocery list and meal plan, those meals will be in there somewhere because they're fast, easy, tasty, and fit nicely in my calorie budget. I have even more meals that we make occasionally - not weekly, but at least once a month - that get rotated in for most of the rest of the time. The rest of the meals are all new to keep from getting bored, then frustrated, and quitting. They're planned in advance, look up recipes and plug in calories in my tracker often while at work on my lunch break on a Thursday or Friday afternoon when I'm assembling my grocery list, to make sure they fit in my calorie budget...but they're new, exciting, and hopefully something I can add to the "occasional" or "weekly" rotation.
TLDR: You can, but that would get boring and you might miss some essential nutrients.