A 9 month title reign now is like 3 or 4 years back then. Hell, the Savage/Hogan storyline that stretched over an entire year from 1988-89 would be done in about 2 or 3 months now.
Why? Because there's more TV, and no more jobber matches. People back then were conditioned to only seeing matches between two "names" either on the big televised shows (Clashes or SNMEs) or on PPV, which was generally once every 3 months. Now that there's what amounts to one or two of those big televised shows every single week, and a PPV every month, feuds are shorter, and so must title reigns be.
That's why it feels like HHH has been champ forever...because in those terms, he HAS.