physics involved pretty easy? i dont think so!!! nmay be the math.... i could understand very well what u have said.. but its all fact... tey are given in the books.. the reason as to why it happens cant be told that easily.. the simplest reason being.. ppl dint know abt short channel effects when they first proposed these theopries.. then they found something abnormal is happening.. and lead to other resaearch aspects.. so we cant take anything for granted.. ther is still much to know even in this simple topic. dont take anythjing for granted.. even this would be proved wrong or who knows.. may contain soime discrepencies! so get to know it always and not think anything too easy!
i mean under estimation
/Am