[dredmorbius]

Evolutionary changes are virtually solipsitically beneficial, by definition.

They may be a local optimum, or adaptations to circumstances which existed at one time, but no longer, or be the result of a long chain of path-dependencies (effectively: multiple local optima jumps, a/k/a "the adjacent possible"), or even non-heritable benefits, such as "don't be under that big sky rock when it comes down" (luck plays a selective role, but features little if any heritable characteristics).

All that said, I'm not making any argument for or against meat eating, other than to note that the evolutionary support of it suggests that it was certainly useful at least at some point in the past.