eeheng, it actually depends on how deep you understand this car characteristic. It is same as like why someones is willingly to go and buy back a old rusted AE86 or Toyota Supra and rebuild it completely and drive it out again.
Example for me, why i bought my SEG is because of my house has another Toyota Olskool.. A KE20 4 door. It has been ridden down from my dad > mom and to me. It suffered a lot in the past.. accident, engine died... and still.. it is still there.. right at my house and still can be ride. That's what makes my mind up to buy my Corolla. That is what affect my trust towards these Toyota car. They just tough and last for long long time... and not like some aluminium can car which will starts falling aparts after a short period of time. And not always we can have money to fix our car, and that is the time this little toyota engineering comes to magic, thou they are noisy in those damaged parts.. but they still can be forced to run for a long time. That is something u can really get on other car..
As for the 2nd reason, SEG share the same chasis and everything with AE111. That includes all 2 door out there on the market with same chasis. So the parts is a lot. And it can be a powerfull 1.6cc car there with a sleeper body. So in return, you get a family car + a powerful toy there.
That's what all i have to say... :) but bewarn that the poison you are going to face once u have a new 20valve 4age engine inside.. U might crave for more power out of it...