Another reason why people also use AE86 because their is also brake upgrades for these struts.
Whereas their is little to none for KE70 struts.
Other struts that fit and have 51mm diameter are XT130 Corona and RA60/65 Celica (which is what I have) and also have their respective brake upgrades. People just general chose what they can get "cheaply at the time".
Also I believe that Golf/Rabbit shock are a short stroke option being 45mm, How much shorter I am not aware.
As only this from a fella I knows 1200 ute which is also 45mm.