Well, I don't know what's up with the LBS! You're a paying customer, right? They want to sell you stuff, well, that's fine, but they should always be patient and courteous, and when you hand them your credit card, they should thank you politely.
I can't speculate what happened to your BB; maybe you didn't do the job right, maybe you did. But I don't think fenders would have prevented it.
That said, I won't commute without fenders. I like them as much as you hate them. You probably don't need them. But I do.
This post gets it on so many levels it just might be 'Best in Thread'.