Some comments from @sipa in #12702.

___

Yes, I think `importmulti` is superior in every way, except:
* Slightly less convenient to use (it requires redundant information, as you have to explicitly state what you want to import, and then give the keys/... to enable that).
* ~Doesn't support P2SH-P2WPKH yet~. Added in #14454

The latter can be fixed by just adding support for that case. The former can be improved by adding 'default' cases (e.g. if you prove a WIF private key, it can permit omitting the address, ...).

if (strOldWalletPass.length() < 1 || strNewWalletPass.length() < 1)
        throw std::runtime_error(
            "walletpassphrasechange <oldpassphrase> <newpassphrase>\n"
            "Changes the wallet passphrase from <oldpassphrase> to <newpassphrase>.");
    if (!pwallet->ChangeWalletPassphrase(strOldWalletPass, strNewWalletPass)) {
        throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered was incorrect.");
    }
    return NullUniValue;
}
static UniValue walletlock(const JSONRPCRequest& request)
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() != 0) {
        throw std::runtime_error(
            "walletlock\n"
            "\nRemoves the wallet encryption key from memory, locking the wallet.\n"
            "After calling this method, you will need to call walletpassphrase again\n"
            "before being able to call any methods which require the wallet to be unlocked.\n"
            "\nExamples:\n"
            "\nSet the passphrase for 2 minutes to perform a transaction\n"
            + HelpExampleCli("walletpassphrase", "\"my pass phrase\" 120") +
            "\nPerform a send (requires passphrase set)\n"
            + HelpExampleCli("sendtoaddress", "\"1M72Sfpbz1BPpXFHz9m3CdqATR44Jvaydd\" 1.0") +
            "\nClear the passphrase since we are done before 2 minutes is up\n"
            + HelpExampleCli("walletlock", "") +
            "\nAs a JSON-RPC call\n"