It's not about HCI per se
It's interesting to examine why some people like the HCI model.
Part of the allure is having an entire stack supported by as few vendors as possible. Very few HCI vendors fit that description.
The other part is significantly lower OPEX. Again, not all HCI vendors shine there.
And for CAPEX - the better HCI vendors that fit both aforementioned criteria tend to be on the expensive side. So it's not about CAPEX savings.
It's also interesting that the complexity of certain old-school vendors has quite a bit to do with certain solutions becoming more popular (not just HCI). Compared to certain modern storage systems, you may find that the difference in ease of consumption is minimal.
Be careful that just because you like the HCI dream you don't give up things that have kept you safe for decades.
Case in point: several HCI and SDS vendors don't do checksums! (Even VSAN and ScaleIO only recently started doing optional checksums).
That's like saying I like electric cars, and in order to achieve the dream of having such a car I need to give up on ABS brakes.
Or things like proper firmware updates for all the components of the stack. Again, many solutions completely ignore that. And that inability can significantly increase business risk.
Disclaimer: I work at Nimble but if I didn't there's only one HCI vendor I'd go to work for. One. Out of how many?