If I'm pitching something to a prospective client or debating some technical issue with another engineer or inspector, I don't need to be seen as the young/crazy guy. I need to be seen as a professional and even though I will never be a suit & tie, white-collar professional, I can definitely clean myself up a bit and find a way to look good/cool (IMO) without looking strange. Don't get me wrong, it takes a lot for me to personally think "gosh that person looks strange" but I deal with way too many conservative/traditional folks (e.g bankers, business people etc...) and I think the piercings were ultimately starting to get in the way.
It's unfortunate, but just like the long hair, the piercings would be fine if I was just a worker in the field, but I'm the guy in charge and I need to look more like what people expect to see. Maybe if I was a bit less physically intimidating (i.e. scary looking) I could get away with things like that, but as it is, with my height and my build, I'm pretty much stuck looking like I could break most people in two (especially if I'm scowling/thinking) so I have to consciously pull myself back from the "leather-clad tattooed & pierced biker" look and go for the "clean-cut competent professional that we feel comfortable hiring" look.
So, yeah. I'm pretty much cool with the change, but I still feel weird that I finally did it (I'd been thinking about it for a couple of months already). Fortunately I can't really tell the difference and so far I haven't missed them at all (so that's good). I think I've missed my beard or my goatee more whenever I've just shaved them.