addmultisigaddress creates an address respecting the setting, being unable to generate a specific type of address without also adding it to the wallet seems wrong.

I suppose in the future `addresstype` may be refactored to be wallet-specific, which would leave this non-wallet rpc call without an argument. Perhaps there should just be an optional parameter to set it.
{
    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() < 2 || request.params.size() > 4) {
        std::string msg = "addmultisigaddress nrequired [\"key\",...] ( \"label\" \"address_type\" )\n"
            "\nAdd a nrequired-to-sign multisignature address to the wallet. Requires a new wallet backup.\n"
            "Each key is a Bitcoin address or hex-encoded public key.\n"
            "This functionality is only intended for use with non-watchonly addresses.\n"
            "See `importaddress` for watchonly p2sh address support.\n"