Lync is still buggy? I haven't used it in about two years, but I'd have thought Microsoft would have solved those issues by now.
WebEx wasn't as convenient but at least it worked correctly the vast majority of the time.
You answered yourself - no, quality is not life and death (at least not fast death) for this product. :)
When there's a rare issue, its usually a headset not working, which is probably more a user or windows problem.
My company has about 4000 users in 100+ countries so maybe it's bandwidth/scale in part. i see a lot of stuff like skypefb crashes or doesn't render correctly when you try to screen share, etc especially internationally.
Not 100% certain part of it isn't due to us cheaping out on infrastructure to run it.