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.
missingInternal = 0;
        }
        bool internal = false;
        WalletBatch batch(*database);
        for (int64_t i = missingInternal + missingExternal; i--;)
        {
            if (i < missingInternal) {
                internal = true;
            }
            assert(m_max_keypool_index < std::numeric_limits<int64_t>::max()); 
            int64_t index = ++m_max_keypool_index;
            CPubKey pubkey(GenerateNewKey(batch, internal));
            if (!batch.WritePool(index, CKeyPool(pubkey, internal))) {
                throw std::runtime_error(std::string(__func__) + ": writing generated key failed");
            }
            if (internal) {
                setInternalKeyPool.insert(index);
            } else {
                setExternalKeyPool.insert(index);
            }
            m_pool_key_to_index[pubkey.GetID()] = index;
        }
        if (missingInternal + missingExternal > 0) {
            LogPrintf("keypool added %d keys (%d internal), size=%u (%u internal)\n", missingInternal + missingExternal, missingInternal, setInternalKeyPool.size() + setExternalKeyPool.size() + set_pre_split_keypool.size(), setInternalKeyPool.size());
        }
    }
    return true;
}
bool CWallet::ReserveKeyFromKeyPool(int64_t& nIndex, CKeyPool& keypool, bool fRequestedInternal)