The problem is wiring isn't defined properly. It's not in the list of programmers. So it may have been done to fix a timing error, but introduced a bug with 100% failure rate. The stk500v2 simply works. When programmers.txt gets updated to define wiring, I'm sure it will fix everything. But until then, this is the only way to get it to work.
The problem isn't in programmers.txt. The definition for the "wiring" protocol is in avrdude, specifically avrdude.exe and avrdude.conf. Only versions of avrdude 5.11 or later seem to know about "wiring", though.
The problem is that the version of avrdude shipped in this ERW 1.0.2 distro is only 5.10. For maximum compatibility, it should probably be using the same version as the one that shipped with the "official" 1.0.2, which is 5.11.
I just replaced the 5.10 version with the 5.12 version I had installed separately as a stand-alone version. Being a later version it understood the "wiring" parameter specified in programmers.txt. That worked (just remember to rename the newer avrdude.exe to replace avrdude2.exe to fit in with the "wrapper" scheme in ERW 1.0.2.)
Your solution of editing programmers.txt so it specifies "stk500v2" instead of "wiring" will work (well, work as well as it always has in the past), but has the disadvantage that you don't get the timing bug fix that the move to "wiring" was addressing. If that bug doesn't affect you, however, it's no big deal, of course.