Bitcoin Cash is a much more advanced solution that simply raising the block size and doing nothing else, even if raising it is critical.

The limit set in place by Satoshi was never meant to remain, but to be gradually increased and not stand in the way of actually scaling. It was a short term solution to solve a particular attack vector that Bitcoin would outgrow over time. Research suggests that we might not even need to keep it at all anymore, but it's definitely possible to scale past it.

It's even possible to do so without hindering people from running half functioning so called "full nodes" that don't actually generate blocks, when this was not part of Bitcoins security scheme to begin with and they really do not count as nodes at all per the design PDF because they are easy to create without as much investment risk as running an actual mining node, or even running a simple "miner" connected to a pool.

The reason this is not being done is more political than technical. At this point it makes sense to let ticker BTC do its own thing and perhaps find other clever ways of scaling. BCH can live on as its own thing. It is Bitcoin, as far as I'm concerned, even if it doesn't bare the exact same name. It has already proven many experts wrong and could continue to do so in the coming years.

The best argument I see against Satoshis scaling solution is probably that the network should not rely on mining nodes for security. But much better then would be to find a way to let regular users be simplified "miners" more easily and for such "miners" to have influence even if they connect to a pool. DPoS might be an even better solution and would also limit the "wasted" energy spent on mining, even if it could per the original design be said to contribute to security by giving block generators an initial expense.

In any case it will be interesting to see where both systems head next and also whether the exchange tickers can eventually be used as a hedging instruments against one another.