Whether to have PS's, and how many, depends on when you're going and what matters to you. We have to go during busy times due to the school calendar, and we hate waiting for things. On the other hand, we don't want to be tied to our itinerary with too many PS's. We've found that what works for us is making a few PS's for the places where we really want to eat, and then eating the rest of our meals at counter service. Our June trip is for 9 days, and we've made 4 PS's. We enjoy character breakfasts, so we have a PS for Donald's. We love Sci Fi, so we have a lunch PS there. We want to try 'Ohana this trip, so we have a dinner PS there. And we have never seen Fantasmic (like I said before, we hate waiting for things!) so we have a Fantasmic Dinner Package PS at H&V. The rest of our meals will be counter service, unless we want to add a PS or two when we actually get to WDW. That's an option too.
I don't think a few PS's at your top choices will seem restrictive; it doesn't to us. And it will keep you from wasting precious WDW time waiting to be seated, or having to eat every meal at counter service. Plus, as ScottWDW said, if you decide that you don't want to keep the PS when the time comes, just don't go. Unless it's one of the meals that requires a credit card deposit (Cindy's breakfast or a Fantasmic package, for example) you won't be out anything.