There's like...three fairly seperate ideas here.

1) Is financialisation of food good?

2) Is welfare/a social safety net good?

3) Shoud weldfare be provided as cash or in-kind?

Hitting them each in order:

1) The finacialisation of food seems clearly good. There's two main mecahnisms for this - first, large producers and consumers of food can bring future prices forward, locking them in and avoiding volatility. A farmer trying to decide whether to plant wheat or soy will want to know what the relative scarcity of these crops will be at harvest time. Future markets let the farmer determine this (using price as a proxy), and lock that price in. Equally, large consumers (mills, food processors, etc.) can go through the same process, smoothing out consumption by adjusting the timing and mix of what they process, and again, by locking in future prices.

Second, speculators also participate. Contrary to what some people seem to think, speculation in food is also valuable. Consider, for a moment, the Russo-Ukrainian War. It had a big impact on global food supplies, and the best possible thing that could have happened is if, well before the war broke out, people had speculatively planted extra wheat. Without the financialisation of food, there's no incentive to do so, nor any mechanism to funnel resources towards it. On the other hand with futures markets, a hedge fund could, say, look at satellite immages showing Russian troop movements towards the Ukrainian border and bid up wheat futures. A farmer with no idea what's going on in Eastern Europe could see the rising futures price, sell some what futures, use the money to buy extra seeds and fuel, and use those to plant a few extra acres, thereby ensuring that there will be extra wheat if a war does happen but (importantly!) costing the hedge fund (not the farmer) if no war breaks out. And equally, note that the use of futures markets and hedging actually did help smooth out prices once the war did happen.

For a further example, for stupid historical reasons the only food commodity in the US with no futures markets are onions. The prices of onions are more volatile than other food commodities.

2) None of this, however, has any real bearing on whether a welfare system or social safety net is good; they clearly are. But while we might argue (and I'd agree) that the government of any functional country should ensure all residents have access to, at a minimum, basic food, that doesn't tell us much about the most efficient way to ensure there's enough basic food go around. Egypt is the largest net importer of wheat, and also heavily subsidises basic staples, to the tune of billions of dollars a year. But that just means Egypt - more than almost any other nation - benefits from the financialisation of food. There's no contradiction here!

3) Economists are pretty united that cash payments are more efficient than in kind benefits. Coming back to Egypt, around 2/3 of the population qualifies for deeply subsidised bread - 5 loaves of flatbread per day, for a cost of less than 1 US cent per loaf. That's excellent news for every poor Egyption who loves flatbread; less good for anyone that doesn't care for it. If instead of paying bakers to produce loaves below cost you gave the money directly to the recipients, they could use it to pay for food of their choice. (Some might also use it the money to gamble or buy drugs; I lean towards a less paternalistic role for government, but reasonable minds can disagree here.)

So yes, it's reasonable to expect that in a country like the US, there should not be a single person without access to, sure, enough water, rice, and potatoes to sustain life. But access could mean many things, and it seems unlikely that dropping a big bag of rice off at everyone's door every month is the best way to do that. A better option might just be making sure that there is no person so poor that the price of such staples might be unaffordable, and that can be ensured in many ways (eg, subsidies, vouchers, food stamps/SNAP, cash payments, UBI, etc.) But another way of ensuring people can afford food is making sure food is relatively abundant and food prices are relatively stable, and the financialisation of food is one way of helping bring that about.

One further point: It might be tempting to think that some resources (water is often mentioned) should be free at point of use for consumers. But note that all resources are finite, and one way of ensuring relative abundance is ensuring they aren't wasted. Free or unmetered resources will inevitably be wasted by some. So while it may be true that every human on earth should have access to sufficient safe drinking water (I think it is!), not only does it not follow that drinking water must be free, making drinking water free could make it harder to ensure everyone has access to drinking water.

The more important the goal, the more important it is that we choose the right mechanisms to achieve the goal.