Retrofitting oem running boards - fixity question

[noddyunplugged]

Hi all,

I'm going to be (finally) retrofitting oem running boards to my '01 E53 sport whilest I'm off over Christmas.
Has anyone read the actual BMW guide for this task?
It notes that the non-running board arch trims are held in using 'expanding rivets' these are the type that have a seperate pin/stud going through a plastic 'washer' that has spreaders on the reverse side so that when u push the pin in flush with the washer the spreaders are forced to full extension thusly holding the fixer in place. Now the destructions say that when you replace the arch trim with the running board version use 'blind rivets' and these are a regular looking more permanent type rivet only these are actually plastic and should you ever need to remove them you'd have to drill the buggers out!

So anyways, my question is; if the arch trims were originally in with seperate stud type expanding rivet, why the heck use blind rivets when you put the new trim back on?!
I'd rather use the expanders to be honest as I've never been a big fan of rivets - in the long term they're a nuisance! But regardless, seen as how they're only pennies each I've gone and bought enough of each to the job either way. I just wondered if anyone could actually validate the reason for using the more permanent type?

Noddy