It is better, but far from sufficient in the long-term. And there are ways to timestamp any given data, without abusing Initial Blockchain Download. If users will abuse the chain too much, then just encouraging people to switch to OP_RETURN won't be sufficient, and then, there are more things, which can be done, for example by making more lightweight nodes, which would require less resources, and which would accept some proofs, instead of storing everything.

In general, I expect there will be some abuse, and some people will make a lot of unspendable outputs, no matter how often they will be encouraged to use OP_RETURN instead. And then, if it will be needed to make further changes, to stop the abuse, then they will be taken, when node runners will start running out of resources, and if there will be a need to encourage more people to run nodes. Because here and now, many people don't want to process over 600 GB, just to get the ability to share the chain, and introduce new nodes to the network. Which means, that if the chain will grow too much, then further actions will be needed, to keep the network decentralized enough, and to scale it properly.

You need that only in the current implementation. But it can be changed in the future, and it will change, if more people will want to do something with the problem of spamming the chain. Because here and now, the system is wide open to non-standard transactions, which will push a lot of data, and which will send coins from zero satoshis to zero satoshis, and every full node will be forced to process that Bitcoin-unrelated traffic. There is no UTXO set size limit, and there is no total chain size limit. And people don't have unlimited resources, so such things can be restricted in the future, to allow running full nodes by enough separated entities, and limit that kind of centralization pressure.