Majority are not 'motorcycle people', just got into old bikes because they are cool (at present )
Don't know or care whats right, just want 'THE LOOK' :
Correct size tyres will last longer and provide better handling.
Oversize tyres will wear out quicker and usually not handle as well and, make bike slower
(although if people have no clue how it should go round corners they won't have anythig to compare with)
Rims are just too narrow for wider tyres.
I may be an 'old fart' but I have worked on these things since they were new.
You can do whatever you want, fitting wider rims should be first option, then even stock tyres look wider
Fitting a stock rear rim to front will be an improvement with a 90/90 tyre, should be plenty available cheap
I've got a couple of WM2 steel rims because I fitted WM3 alloys 8) (if anyone needs them?)