"Yes CoolJazz it is consumerism and never having enough. But maybe I am just a simple soul who is easily satisfied."
Ohhh @URSick, it must be wonderful to be such a saint. If you ignore all the judgementalism, of course.
Re: kids having their own rooms. Whilst this is not essential, let me tell you that it makes things a lot easier, especially when they are teenagers, with lots of homework and revision to do. And when there is friction between siblings, it is very useful if you aren't trying to referee between them at bedtime, because they aren't continuing the fight in their shared bedroom, but have each got somewhere they can get away from their sibling in.
Extra bathrooms - also very handy especially in the teenage years, when personal grooming becomes much more important to them. Getting a bunch of teenagers up and out of the house for school is a lot easier if they aren't fighting over who has the bathroom next, and whether someone has been in the shower, like forever.
A playroom is great when they are little - if you are really tired, in the evening, you can shut the door on it, and go into a tidy, grown up front room - do not underestimate the benefits of not having to do a load of tidying up before you can relax in a relatively toy free space. And when they are older, it is great for them to have their own den/sitting room - when their bedtime gets later (9-10pm), it cuts out a lot of the discussions about who gets to use the TV, and what gets watched - they can be in their den, with their x-box or whatever, or watching teen rubbish on the TV, whilst the parents can watch what they want to, in their sitting room.
And I am sorry - you may insist that you are not jealous, but you sound utterly jealous, based on what you have said here.