What I'm worried about is that currently, with the new A20 block placement system, we don't have really a choice for higher tier materials.
If you want to build an all-concrete base quickly, you can't use iron frames anymore, right?
So in A20, if I understand it correctly, you have these two options.
Option 1: place all the particle wood blocks and do the full upgrade path to concrete, wasting materials and time. Yes, TIME! Not everyone has a nail gun handy in the first few weeks, Roland. That's actually the best case scenario.
Option 2: is to directly craft the concrete blocks in the mixer (if you have one) and place them to build your base. But as I said, you completely lose the opportunity to quickly handle misplacement errors, and you'd be forced to destroy each "wrong" block with (again) a huge loss of time.
So, in the end, if this is how it works, I'll try to live with that, but IMO you (TFP) lost an opportunity to make the building system even more sleek.