I'd say it's to do a lot with advances in turbos. Most small engine cars have turbos now that rival anything even a decade a go. This means you can get by with much smaller engines and get similar performance.
True, turbos (even dual compressors as in the case of VAG's TSI) have much impact, but even non-compressed engines (in lower end models) are vastly better-behaved than old car engines.
I once had a Sunbeam Avenger which was horrible in very many ways (not least because of the build quality in English unionized car plants) and an uneven torque curve (with a peak and a not that high peak as such) was one of its problems.
I once had a Sunbeam Avenger which was horrible in very many ways (not least because of the build quality in English unionized car plants) and an uneven torque curve (with a peak and a not that high peak as such) was one of its problems.