But back to Romans: it's both very plain in meaning and message and in places, "hard to understand" (as Peter famously characterized Paul's writings). But not impossible. As mentioned, those places simply require more thinking, more lingering upon the text and context, more Spirit-helped brainwork. Logic is involved. (Spiritual understanding doesn't preclude logic.) It's all important, both the plain parts and the more difficult ones; all for the sake of seeing Christ as more lovely, and God as greater and more good, than ever.
That's the way it is not only with Paul's writings but with all of Scripture. The Bible describes itself to contain, in it's wisdom, proverbs and riddles (Proverbs 1:6). To understand it, and thus God, one must "receive," "treasure up," "make your ear attentive to" and "incline your heart to" God's words and commandments. One must call out for insight, raise one's voice for understanding, seek for those things like silver and search for them like hidden treasure (Proverbs 2:1-8). This is all done because of, and in order to learn, the right and proper fear of Yahweh. To behold his beauty.
All this is true work! God never said that insight and wisdom into his ways would be handed over easily and casually. He has always been a God who has been all about being sought as treasure, as more desirable than the finest silver or gold. That's how truly worthy he is.