Wow...but when it comes down to it people probably don't care about the domain as much as Toy R Us thinks. People find the toys they want, then price compare on Google. Or if they want to skip that step, they'll just buy it from Amazon.
Where does your information come from? According to their website they were acquired for $6.6B in 2005. The acquisition was probably at some multiple of revenues...so how did they get up to $13.646B? Besides, earnings are more important than revenues. Look at GM, they lost $20B on revenues of almost $150B. You think it would be wise for them to buy some domain like "cars.com" when they already have gm.com (toys.com just forwards you to toysrus.com)?