Trump wants his wall in exchange for literally nothing. Why would Pelosi give him the opportunity to pull another stunt like he did with every given oppertunity?
He threatened to veto any bill that wasn't Goodlatte's, then wanted full funding for 3 years of DACA and recently married both shit offers with the Bridge Act combined with elements of Good latte.
Can you imagine if the courts struck down DACA and he gained all the bargaining power? He'd want to end birthright citizenship in exchange for DACA.