It's a good question and one of the drawbacks of IPFS. Yes, perhaps a good system could be added for using BCH to pay for hosting on IPFS.
If you didn't use ipfs you would run a central server, right?
Yes, that was the original plan. If you look at the source of the protocol page there's an action commented out for setting a base URL, basically a content hosting provider.
what's the difference between running a central server and running an IPFS node? You need a server anyhow. With IPFS people can help hosting their own files.
One benefit is that it doesn't require DNS or even a public server. You can run a local Memo client that uses IPFS. Another nice thing is it has built in easily parsable hashes.
Can I run this local Memo client right now?
.. on IPFS?
You can run a local client. Not using IPFS though. Also lighter clients can be built.
