It’s just a speed bump. It’s an obstruction.
It’s bad for the user.
It’s a sign that says, “Turn back, because this is how the rest of your experience will be.”
Just get rid of it, okay?
Oh, and if you have a splash page that says, “Loading,” what are you doing? You’re saying, “Thanks for taking the time out of your busy day to come to my website. You didn’t have to, you probably didn’t even need to. You just wanted to. Now wait, dammit.”
And if you need a more tangible business-related reason to get rid of it: It’s bad for SEO, all right?