My biggest disappointment with MPTCP was that seemingly, you need both the old and new address to be available when doing handover. So you cannot suspend your laptop, go to a different place, and resume the TCP sessions on the new Wi-Fi.

Of course you can do that. There are different timeouts (MPTCP level, TCP (and SSH) keep alive, etc.) to prevent having dangling connections for a while, but they can be changed if needed.