Power Amp Doubling Output at 4 Ohm

Hi, all,

Another random musing. From time to time, I see ads that mention such and such power amp can double its output from 8 ohm to 4 ohm (and even double again from 4 ohm to 2 ohm). To me, this does seem to be a highly desirable, quantifiable, quality. I don't know anything about the engineering behind equipment design, so here is my question. Is this an important parameter to you? If not, why not?

Thanks for your inputs.