There are some interesting replies expressing preferences and resistance to change over your research analysis :( Maybe Windows 8 did Microsoft more lasting attitudinal harm than can be undone overnight?
My own opinion is that you have moved back into the right direction. Clever (abstract or veiled concrete) icons often lose their semiotic through the often over simplification process.
Relating ‘sharing’ to ‘forwarding’ reduces the visual dialogues and concepts our users need to learn or remember across platforms and communication apps. That your research backs up the design is reassuring and we may indeed be headed to a standardized icon concept.
I share the concern for our older users expressed earlier not least because they may have less time left to enjoy your work. A comment here suggests a 1px stroke to be visually pleasing. 1px helps with resolution at smaller scales and perhaps older users and our fellows with lowered visual acuity may struggle at those resolutions in some conditions? Perhaps, where visually acute graphicists rule the UX and usability silos, visual fashion will continue to outrun accessibility? (And runs for cover!)
Good article. Good work. Plenty to reflect upon. Thanks for sharing :)