Personally, I don't see anything wrong with modding, and would encourage EVERYONE, yes, even the ones with a brand-new spanking rare system, to put in mods. Every single system I have is modded at the very least with a region-free chip/switch.
That said, I think cosmetics should definitely be considered. For example, a lot of people put in simple rocker switches like this below which I think are ugly. It just looks so out of place.
So when I put in my umpteenth multi-region + 50/60Hz switches for my saturn, I really looked around for some switches that wouldn't look awful. I ended up with this.
I know that some people put the switch inside the battery bay for the saturn, and there's the switchless mod too, but those are annoying for functional reasons -- I just want to switch and start playing. Not open the battery door, close it again, or having to press buttons for multiple seconds to switch regions/Hz -- that's just irritating. Functionality still trumps anal desire to make it look completely stock (why even bother modding in the first place, then?)