Its nice to split up the bitcoins into separate wallets.
What is so nice about it ? Logically speaking,the reason I use multiple wallets is to be secure just in case but mostly for my transactions/Savings.I maintain an online wallet for my daily transactions while whatever I earn through gambling or promos I save it in a offline wallet as cold storage (security funds).Besides this,its a good habit to use distributed systems as a way for securing accounts.
why do people use so many bitcoin wallets I can,t know but I have no mere bitcoin. i am using only one wallet but other person is why use more bitcoin I don,t know