[Terry Reedy]
There is certainly some disconnect on the issue.
FWIW, whenever I done talks on 3.0, it is common to get an aversive reaction when the new syntax is shown. I pitch it in a positive light, but you can sense churning stomachs.
get arguments pro and con exposed and argued.
One risk is that maintainers of third-party modules may be disincentivized from converting to 3.x. For heavy users of %-formatting, it may be easiest just to stay in the 2.x world (unless an automated conversion tool emerges). Another thought is that it is premature to mandate that others convert until we ourselves have updated the standard library. That exercise may be informative and provide some evidence about how easy, how hard, or how possible it is to convert. Also, conversion may be difficult in cases where the existing syntax has been exposed to end-users and is a guaranteed part of the API (perhaps in config files, templates, file renamers, mail mergers, etc.) In our own code, logging formatters spring to mind. Raymond