Soundbars are small to meet the target audience. If you want better sound, you need better and generally larger drivers, which means larger cabinets, which means it no longer meets that size requirement. So they keep them small - a compromise. Smaller drivers to keep them small - a compromise. Power handling is then compromised. Bass is compromised and even when you get an external sub, it is going to cover the lower mid region not the bottom octave. If every aspect is a compromise, how can you expect it to compete with an actual, even modest, system? We aren't talking $5000, we are talking $1000 in speakers (AVR excluded in both cases, since you would need it for both) will be competitive with the best soundbars period.
Samsung buying them is likely the downfall of Harman, and if Samsung is your comparison basis, let's just say you have a lot to learn.