I think they have executed well, ie made the most from what they have. I don't think SpringPath was ever that exciting or revolutionary, but the ESG report serves them well. In truth, I've only ever seen HyperFlex in one account, and even then it was a test VDI environment for 100 users (an NHS CSU with budget spare at the end of the year). I come across a significant number of HCI opportunities every year and never see Cisco in them. It's nearly always Nutanix and increasingly VSAN (if you can call VSAN HCI?), as most accounts have a VMware vSphere implementation.
I must say that I have to disagree with you about HCI being a stupid marketing fad to sell SDS. If that is your true opinion, you're in for a shock over the next few months and years. As I see it, Cisco's HCI implementation is fairly rudimentry, no shocks. It ticks the basic boxes but no more. Look at companies like HyperGrid, and to a lesser extent Nutanix. They see HCI hardware unpinning a much more ubiquitous private/hybrid cloud strategy, an applications/ services drive strategy. They want to compete against the AWS and Azure's of this world. Self service provisioning, automation and orchestration, in an on-premise environment to enables better control. They are already one step ahead of Cisco and the simplicity with which they have delivered their solutions puts them ahead of the likes of VMware/IBM too. I see HCI taking large chunks out the traditional server+storage market. Whether, the start ups are successful in their own right or just get swallowed up, this is the way the market is moving. However, I guess there will always be a group of people who pine for LUNS and yearn for Fibre Channel, and, for a while yet, they'll have plenty to kit to fill their boots with.