Good points all around, although I have a nuanced disagreement with your assertion that "good defenders" aren't affected by the rules you cited. Particularly in the NFL's case (my area of expertise in football is at cornerback where I played for 7 years and have coached the position at various levels for the last 8 or so), there are different types of defenders, techniques AND schemes that all play into that rule.
The "Illegal Contact" rule benefited players that were smaller, quicker, had more fluid hips and better footwork, and punished players who were bigger, stronger and more physical. One could argue that it shortened the careers of some of those latter types of corners who couldn't adapt to the change. It also affected schemes and playcalling, as some defenses (cover 2, for example) were more dependent on a physical corner presence on the outside vs other defensive schemes.
At least with Golf it is for the betterment of the game as they would be promoting a higher skill level (IMO) truer to the original intent of the sport. In the NFL's case, they were just trying to increase scoring to make the game more exciting and marketable, even though it actually hurts the sport (horrible illegal contact penalties called every week, defenders are at a marked disadvantage, and it decreases the ability to slow WRs down as they advance upfield, thereby increasing the collision speed of hits across the middle and down the field which has added to the inherent danger of the game). Anyway, of course this hasn't eliminated the big, physical corner from the game as they are as prevalent as ever. But they definitely had an adjustment period. The same would apply to a golfer who anchors a belly putter currently: if they can't adapt, their career will be shortened.
I will definitely defer to your expertise on the nuances of the rule (I was a tight end in my day - which ended a long time ago because I never played past high school, and wasn't very good anyway) and how they affect specific types of players. But, fundamentally, I agree with you that it comes down to simply being able to adapt.
Like Erik has said several times, rules change in sports all the time, and while they aren't all nearly as controversial as this one seems to be, they all involve players having to adapt to the change or retire.
Personally, I really don't care if they change the rule or not, which I guess means that I'm on the side of not banning anchoring. It just doesn't bother me and I don't care if some people do it or not. (I think certain members with Irish names who never post in these threads would be happy to hear that )