Actually, the one thing i think most people are paying for when it comes to indesign is adobe's type engine, which behaves predictably and also supports the kitchen sink of opentype features. It's easy to dismiss ot support as a convenience function (it is at some level), but it's the killer feature for any typographic application where you want to use the full range of type available to you in the font (family?) you paid oh so much money for.
I once designed using a version of futura that had the small caps & osfs in the glyphs menu (untagged!) and was livid when i had to set nearly a paragraph of text by inserting each one at a time. Since the last time i checked when i was in grad school [1], this was still an outstanding issue in scribus (shaky opentype smcp/dlig/salt support) and it's really the one that kept me from ditching indesign. As it was, i would probably have jumped ship and used latex/xetex had i not been trying to individually rag each line.
It's not like you can't make nice work in scribus, but it may also be more convenient to do it in a program that has solid support (and mostly tuned ui) for the features that many typographers use.