Yes, because there are services you can get at a traditional bank that aren't available from online banks. You don't need them often, but when you do, you do. Examples: getting a medallion stamp, bank check for a home downpayment that you really don't want to risk getting lost in the mail, depositing a foreign check.
IMHO they are best used paired with an online bank - I use Chase and Fidelity. To avoid Big Bank Fees (that can eat you alive) you can find a way to automate a process that meets their criteria for free checking and doesn't risk overdrafts. For example, with Chase you can direct deposit your monthly paycheck then auto transfer it to your online bank. I think direct deposits from your online bank might work too, but I haven't tried that.