Some lenses increase in value, but not many. IQ and impact are important, but one must reach a level of expertise where the magic of certain lenses can be fully extracted. Anyone who wants to be seen with an expensive camera and can't utilize its inherent qualities is lame. I can't tell you how many pro and fine art photographers are out there earning a living and satisfying customers with gear that is obsolete or regarded as junk in many photo forums. There is no substitute for talent. In particular, photographing people is a special thing and IQ often means nothing.
Conversely, I suspect that most professional photographers use equipment that is relatively up-to-date. For pros, the only thing that matters is the final image. Economics notwithstanding, if a more expensive piece of equipment would deliver a better IQ or increase the Image Impact or make it easier to capture the desired photograph (elevate consistency/higher keeper rate), most pros I know would opt for the better hardware in a heartbeat.
Yes, there isn't a substitute for talent ... skill and experience. I suspect, (again), that most pros with 'obsolete' equipment can outshoot a collector with newest, shiney, top-of-the-line gear.
When I was shooting news (back in the film-only days), nearly all my assignments were to photograph stories of people. IQ has an importance in all images. But the significance of IQ varies by each subject. Generally, and in my opinion, the greater the Image Impact ... the less IQ is required for the photo to be successful and vice versa. Nick Ut's Vietnam War image of the screaming, naked little girl, escaping a naplam attack, has horrible IQ, it is unsharp, muddy and grainy. If the image was sharp, less grainy with better contrast would the image improve? Certainly, but not significantly. Eddie Adams image of the South Vietnamese general shooting a communist suspect on the streets of Saigon, is in focus, not grainy with good contrast. Would his photo be less successful if it had similar IQ as Ut's photo? Yes, but not significantly. And, there are always exceptions to all general statements.
My point is, as a former pro people shooter, I much rather capture my people images with a high IQ than a lower IQ. IQ always matters in varying degrees.