I find the unrelieved use of netherbrick (block, slabs, stairs, & fences) in nether fortresses consistent with the [assumed] dark and brooding nature of the structures. [Very suitable for a hell dimension.]
Rather than using red nether brick [RNB] to decorate the current structures, I'd rather see a small chance that a particular nether fortress was constructed of RNB thus adding some variation while preserving the grim-dark nature of the sites …
While this would involve adding RNB slabs, stairs, & fences, these would be useful additions in any case (and a small positive step in adding additional slab, stair, fence/wall variants).
Rollback Post to RevisionRollBack
WARNING: I have an extemely "grindy" playstyle; YMMV — if this doesn't seem fun to you, mine what you can from it & bin the rest.