It appears that it's mainly sedevacantists who are against Vigano. Surely that says something. Sedevacantists seem to expect that only someone perfectly traditional (preferably sedevacantist) in their eyes should be bothered with or paid attention to. I certainly don't think that we should hang on every word of Viganos', since he's likely to get some things wrong. But he does get a lot of things right.
As Sean said earlier in this thread, Rome's [eventual?] conversion should look like that of Viganos' conversion (or words to that effect).
Archbishop Lefebvre held out hope that Modernist-occupied Rome would one day convert back to the Catholic Faith. There's that word "Hope," which many of the sedes don't have. Do the sedes even want modernist Rome to convert back to the Faith, or have they totally given up on that?
Conversions don't happen overnight, and when Rome converts, it won't likely happen overnight, IMO. Unless there's some kind of miracle or divine intervention.
I've felt for awhile now that the Francis papacy is a good thing, because it will wake some Catholics up to the reality and ugliness of modernism. That seems to have happened for Vigano. If someone like Cardinals Sarah or Burke would have been elected to the papacy, it would have been more of a conservative modernist papacy, like that of B16.