“Milhouse, please specify which kehilos followed this script 50 years ago and 100 years ago. ”
The one I know for sure was doing this, not just 100 but 150 years ago, is Lubavitch. In Lubavitch the saying is that one should come to selichos וואקלדיקערהייט. But I don’t believe it was only them. Probably most chassidim were doing the same.
And of course the music during selichos should be appropriate to the occasion; solemn and serious tunes, not jolly rolicking ones. But I don’t accept your assumption that these events are using inappropriate tunes. If there is one place that is doing so, criticize them for *that*, not for using music at all. Don’t include in your criticism those who do use appropriate tunes.
The bottom line is that *every* community has music during selichos. I can’t believe yours doesn’t. It’s just that traditionally this music has been voice only, and now some people are adding instruments. I can’t see what could be wrong with that, so long as the tunes stay appropriate and they don’t use an organ, which was assered when the Reformers copied it from the Lutherans.