We have a playroom, but that's because our children don't each have their own bedrooms. Right now, everyone sleeps in the master bedroom, and toys are kept in the playroom.
It's how I like to organize my house -- Each room has its own specific function. Kitchen for preparing/storing food, living room for socializing/movie watching/family time, bedroom for sleeping, playroom for playing/toy storage. We decided to create a playroom because it seemed like a more efficient use of our available space and it best satisfied my need for organization. I discovered that I really like this setup, especially as I look back on the rooms I shared with my sister and how it seemed like we never had enough space to play because beds and dressers were always in the way. :) It got especially tight if either of us had a friend over.
When the kids get older and move into the spare bedroom (they will all share one room; I'll just cram all of their beds in there), toys will stay in the playroom. I would definitely not have a separate playroom if toys are in bedrooms, too. It seems like more work/cleaning to have toys in both places. I also have a strong preference to focus on one job/room at a time and do it until it's done -- So when I get the urge to do toys, it's nice to have everything in one room. I'm hoping the kiddos will prefer to all help each other clean the playroom, rather than being responsible for cleaning their separate rooms individually. Seems like it would be a better use of time and go much more quickly if 3, 4, or 5 (or however many) children are all working together to pick up toys if they're all kept in one room.
So for us, as long as our children have toys, then a playroom is definitely necessary. My sanity depends on it quite a bit. :rotfl: