I was just into other, non-toy things (MTV and girls) and Pretenders were the final straw. They just defied everything a Transformer was to me.
I remember that pretender-period too. Back in '88, To me Pretenders looked nothing like what a TF was supposed to (as though they belonged in MOTU). These days, I know that sounds silly but that's how I saw them as an 8-9 year old.