I have never agreed with those who say frequent title changes cheapen the belt. If anything, it keeps the produt fresh. I can't imagine watching wrestlng in a time where belts were held for multiple years at a time. I would think it would get boring, especially now. Hell, the only guy to hold it a long time was Cena and because of that reign, he gets mixed reactions despite trying to be the Hogan of our generation.
We all basically agree that the Attitude Era is the most popular of all time. What made that era go was the constant title changes and intense storylines with the top names. The Rock was a 7 time champion, but never more than 4 months I believe. Even good old Stone Cold never held the belt for more than a few months at a time. That is waht the era was about, UNPREDICTABILITY!! Its' what got me back into wrestling as a teen, I was drawn to the idea of "omg, what is going to happen next week?" For a while, I believe the WWE got away from that, almost had a bout of nostalgia giving long reigns to Cena and Orton. However, fans these days have short memories and attention spans, you have to always keep them guessing.
Back to the worth of titles, the title means something when those carrying it are the best performers (face or heel) and carry it as such. If you as a fan can believe the champion as being the best, then it is being used well. That is why when Rey Mysterio was champion, I think it was devalued as it was kind of a huge suspension of disbelief for him to constantly beat guys a lot bigger than him and a lot more entertaining overall. Bottom line, keep the best performers near the belt and have up and comers realy earn that spot by working hard to become great performers in teh ring and out and it will mean something.
Length of title reigns has NO affect on the meaning of the belt. If anything, a long reign means that no one else is capable of carrying it at the time and thus, devalues the belt as something no one can attain.