[...] I know that only photographers see the differences in most of these crazy lens choices 99% of the time. Clients just don't, clients see moments, posing, lighting, composition, post processing etc . This constant hand wringing about a few lppmm, or distortion, aberrations etc is just crazy.
I'm sure that's right, if what matters is the perceptions of clients. Those of us (un)lucky enough not to be professional photographers are our own clients, as it were, and, just like any other interest/hobby, if you get "into" it enough you start to care about all sorts of details that others just don't notice (and, when they're pointed out, don't care). Some distinction that may seem trivial to me might matter to you, and vice versa; and while it's probably true that all manner of differences among lenses and bodies are simply invisible unless you go pixel-peeping - in which case it really is crazy to obsess with this sort of thing if you don't pixel-peep, print small, etc. - some of us do.
And for those sorts of reasons it's hard to answer questions such as "I own body x and lenses y & z; should I upgrade to body A or lens C", especially if what motivates the question is some hoped for change in image quality. In a different life I used to sell cds of classical music, and new customers would always be taken aback when they asked for a recommendation for a recording of some piece of music because, instead of just saying "this one's the best" I would ask them questions about their tastes in interpretation and tried to tell them that they mightn't notice what I notice (and vice versa), care about what I care about, etc.
Sometimes, just for the heck of it, I'll show my other half a couple of photos for comparison purpose (noise, botched lighting, etc.), and as often as not he'll prefer the "wrong" one and not notice what is, to me, an obvious flaw. It's an enviable state, in some ways - often, when looking at others' photos, I'll find myself looking at all the trivial stuff that we're supposed not to care about (and I'm quite sure that I never noticed chromatic aberrations, noise, etc. on HD TV shows until I got into photography a few years ago). But once you get into the habit of scrutinizing details it's hard to stop....