I'm not sure if this has been raised before, I'm sure I'm not the only one who finds this annoying.
Often when I want to briefly check SP, I don't bother logging in. I don't stay logged in for security/privacy reasons.
Additionally, it's intrusive and would deter new visitors from browsing/registering; and hence reduce ad revenue.
Finally, it does nearly nothing to deter rule breakers because most people instinctively skip these kinds of messages.
I think you'll agree that removing this feature is in the interests of both the business and the web community.
Babes I like:
AnnaSophia Robb, Britt Robertson, Candice Swanepoel, Emily Osment, Jennifer Lawrence, Kaley Cuoco, Kate Upton, Katrina Bowden, Lyndsy Fonseca.