It is pretty obvious that allowing domain name registration info in the block chain does not scale.
I guess you should sell your BTC, then, because arbitrary transactions are allowed right now, and they are very likely to always be allowed. If using Bitcoin's chain for DNS is the best way to do DNS (which I'm not totally convinced about), that's how it will be done. There's no way to stop people from sending information via Bitcoin.
Look who came up with that OP_CHECKSIG trick for inserting arbitrary data:
Timestamp hashes are still already possible:
txin: 0.01
txout: 0.00 OP_CHECKSIG
fee: 0.01
If there's an actual application like BitDNS getting ready to actually start inserting hashes, we can always add a specific transaction template for timestamps.
I like Hal Finney's idea for user-friendly timestamping. Convert the hash of a file to a bitcoin address and send 0.01 to it: