Central AC ....Is it a MUST HAVE?

In my September's electric bill there was the usual newsletter from the electric company. Quite frankly I never read these things, but for some reason I picked this one up.
In it was a chart that had certain appliances and how much energy they use. Well the shocker to me is that I thought and have said that central ac is cheaper to run than window ac's, well according to their chart central ac is about equivalent to 5 window ac's. Now I have a home that in our area is considered nice sized, not huge but not small either, and I do not have central ac which was something that was on the future must haves, well I also so not use 5 window ac's. We typically have one large one on the 1st floor that is set for energy save running during the day, and then I have 2 upstairs that get set for 68 degrees and run based on temp. According to my electric company 5 window ac's running for 165 hours per month costs $80.19 the central ac costs $87.41.
That shocked me! I really always thought that the central ac was a cheaper alternative to the window ac's. I know there is a cosmetic improvement when you get rid of those things, but it seems like that is the only improvement. For approx. $12,000 I can have the central ac installed in both floors, and I wanted to do it for the savings AND for the aesthetic appearance. But now I wonder for just 2-3 months of ugly ac's is it worth the expense.

Does central ac make a break your decision to buy?
Is it a requirement on a home that you want to view the inside of?
Or is it just a nice bonus but no big deal if it is there?

I really would like to know what people think on this.

Thanks.