Your point is very valid, IMHO. Given that it's easy and relatively cheap to transfer funds, it's only ever really necessary to have enough funds in your account to avoid a margin call. Any more than that is unnecessarily risking loss due to broker insolvency or fraud (I've read the occasional story about brokers not allowing a client to withdraw his money). You are absolutely correct, lower leverage is going to work against this approach. You could perhaps diversify by having accounts with different brokers, and (for example) instead of trading 3 lots with one broker, trade 1 lot with each of 3 different brokers. Then you would only have 1/3 of your money exposed with any one broker. Not a tidy solution, but what else is there?
I've only ever traded spot forex. However, I believe that it's also possible to trade forex on the futures market. You might be able to find information somewhere on the forum, or post another question for others to see.