I think the old way is simpler in the sense of building on fewer concepts, and therefore allowing an easier learning curve, if you grant that understanding the React component lifecycle is required and inevitable. Once you understand the lifecycle, running code when certain lifecycle events happen is a very small, concrete conceptual leap. Names like "componentDidMount" tie directly into your fundamental understanding of React. If using them to maintain state forces you to deepen your understanding of the component lifecycle, that effort will pay dividends when you have to debug, optimize, understand someone else's wacky code, etc.
Hooks, on the other hand, have to be learned as an additional and separate concept. In fact, each hook has to be learned. You won't have a clue what "useState" and "useEffect" do just by having a knowledge of React fundamentals. If using hooks allowed developers to avoid knowing the React component lifecycle, an argument could be made that they provide a simpler alternative, but I don't think anybody is going to get very far without being forced to learn about the component lifecycle. If someone were to say, "The React lifecycle is hard to understand, so use hooks instead," that would be a false promise. Hooks are something extra to learn, not an alternative to understanding the lifecycle. To the extent that a programmer can avoid understanding the lifecycle by using hooks instead, they are just putting off that learning curve until they have to traverse it later, probably under the pressure of debugging some nasty issue.
Hooks seem to win from another perspective, though, which is that by accepting the cost of adding this new concept to your mental model, you can write simpler-looking code that is easier to keep error-free. To me, that's the trade-off. Hooks are an extra complexity to understand, and each new hook can encapsulate arbitrary complexity and behavior that isn't obvious from reading code that uses them, but the code that uses them can be more concise and perhaps easier to read and keep correct.
Hooks, on the other hand, have to be learned as an additional and separate concept. In fact, each hook has to be learned. You won't have a clue what "useState" and "useEffect" do just by having a knowledge of React fundamentals. If using hooks allowed developers to avoid knowing the React component lifecycle, an argument could be made that they provide a simpler alternative, but I don't think anybody is going to get very far without being forced to learn about the component lifecycle. If someone were to say, "The React lifecycle is hard to understand, so use hooks instead," that would be a false promise. Hooks are something extra to learn, not an alternative to understanding the lifecycle. To the extent that a programmer can avoid understanding the lifecycle by using hooks instead, they are just putting off that learning curve until they have to traverse it later, probably under the pressure of debugging some nasty issue.
Hooks seem to win from another perspective, though, which is that by accepting the cost of adding this new concept to your mental model, you can write simpler-looking code that is easier to keep error-free. To me, that's the trade-off. Hooks are an extra complexity to understand, and each new hook can encapsulate arbitrary complexity and behavior that isn't obvious from reading code that uses them, but the code that uses them can be more concise and perhaps easier to read and keep correct.