When rooms are very dead then omni works as well as anything else and most acousticians make small rooms very dead to smooth out the bass. In this case the omni is an adequite solution. And lets face it it is a whole lot easier and cheaper to make an omni source.

But the small room problem is low frequency only. That is, it is true that one wants a lot of absorption at LF in small rooms, but that does not mean that one wants a lot of HF absorption. In fact the exact opposite is true. So building the correct room acoustics is a bit problematic, but it certainly can be done (see my books). When the room has a lot of LF absorption and little HF absorption, the omni-directional source is a disaster. This is where the directional source is not only desirable but required. In fact in any room which has little sound absorption, the directional source will always sound better.

So you see, that the desire to have an omni-directional response is misguided.