Leaving aside any question of the wall being worth the cost and harm involved, making those counter-offers at all assumes that the other party would be dealing in good faith and would hold to any agreements after getting what they wanted.
I'm not sure the Dems are - or should be - optimistic enough to bet on that. Not after the last few years.
@pstewart my sentiment as well and I’m not proposing that they kid themselves. The point of these proposals would be that they are massive demands that would never be acceded to; they provide an opportunity of countering the GOP vision of the US with a progressive one, and increase the pressure for an actual deal.