This is ONLY my personal experience, and I don't pretend to believe it is necessarily typical, but- I have to say I am usually puzzled by the reports of easily damage AlBooks. My 12" is now about 4 months old and doesn't have a scratch on it. I take the simple step of putting it in a $20 (Tucano) skin case when I take it anywhere, but I don't think that's such a big deal, and furthermore that's a good idea no matter what your laptop. Yes I probably am careful with it, but I don't think inordinately so.
As for the TiBooks, I never owned one, but a friend did (500 MHz). Sure, it showed some age as time wore on, but I don't think it was above-average in that category for all the laptops I've ever seen.
Lastly, I have to mention that while Ti is generally better for most applications (and more expensive) than Al, not all Ti is created equal. I don't know where Apple sourced theirs, or its relative quality, etc.; just a tought.