Hm. Ok. But then there should be a preference where one would preselect the instrument (or channel preset) one would like to see as a default. I might even chose the EVP (IMO an absolutely underrated e-piano emuation, I use it all the time ever since the day it came out), but probably with some different setting.
As you said at the top, the automatic EVP88 thing only happens if you have the box "open library" selected in the create track dialog. If it is unchecked, all this is irrelevant, and you can just choose your preferred instrument/strip/etc
I believe this new "feature" arrived in the 9.1.1 update - I suppose to help new users to have a sound there when creating a new track. I'd just keep it unchecked....
If I recall, GarageBand loads up a piano instrument when a new software instrument is chosen by default, so this would be "familiar behavior" to upgraders as well as more comfortable for new users. And as you say, more advanced users may often either leave the box unchecked, or start from a template with their own instruments pre-loaded.