What irony? Who cares? OS4 offers developers more choice. I fail to see why that is a bad thing.
The irony is AmigaOS4.x developers failing to develop software the way Amiga software is meant to. As for who cares? How many are left to care? Giving developers choice is not always the right thing to do, unless ofcourse "a big mess" is the goal.
As for Firefox, I keep it around for the same reasons someone might keep IE6 around. I always found Firefox way too much of a resource hungry slowmess and moved over to Konqueror back in KDE3.2 days or so. Firefox can be fast at rendering pages, but it's way too sluggish to use. Another annoying thing is that plugins bring down the entire browser; on Konqueror I can kill off the flashplayer without it having any effect on the browser.