"There are no ads on The Internet." - At least that is my policy, and I strongly enforce it with enough ad-blocking.
All jokes aside, I voted no. You want your members to be able to login effortlessly and painlessly. Lastly, should you modify your login page and something go wrong, you wouldn't be able to log back in to correct it (since the login page would be the problem).
That opens the door to a world of possible problems.