I thought Acrobat had ugly UI — stacks and stacks of toolbars for example (this, BTW, about a decade ago — I haven't launched Reader in some time so can't speak to the current UI).

I met one of the engineers from Adobe and said as much — as politely as I could. He said, yeah, we're modeling our UI on Office.

I saw in an instant that they wanted to be seen as a peer, a co-tool, to the Microsoft suite and it all made sense to me.