Is more features the only answer to increasing ACV?
Features usually are not the key to increasing ACV — at least not directly.
In fact, in 95% of cases, charging for 95% of new feature is tough. Because in SaaS, the customer expectation is that the product will constantly get better. At least, every quarter. Part of the reason you agree to a recurring revenue product is for recurring improvements to that product.
But … what customers (with some positioning help) are OK paying more for is more of a solution.
Something that solves a progressively bigger and more important problem for them.
A piece of that is the new features required for that Bigger and Better Solution. But just a piece.