Part of me always believed to make a solo book work you have to let it have an impact on the character it's portraying. While solo books for Wolverine, Thing, Gambit, and Torch are all well and good, the average comic fan knows anything of significance that might happen with those characters will happen in their main team books. Wolverine is actually an expection lately...his book had Enemy Of The State, which had direct impact on other Marvel titles (like with the death of Northstar), and even his current quest should hopefully lead to change (although, New Avengers should step up and remove him from the line-up due to this year long epic).
I remember the early miniseries from the 80's did involve change, Wolverine and Kitty Pryde coming to mind. Kitty's character got to make a significant change in who she would become. What does the current Doc Samson mini do for his character? Absolutely nothing.