PCIe was a bottleneck in consumer boxes, but that wasn't the whole problem. Optane's low latency and write endurance looked great on paper, yet once you put it behind SSD controllers and file systems built around NAND assumptions, a lot of the upside got shaved off before users ever saw it.

"Just make it a faster SSD" was never a business. The DIMMs were weird, sure, but the bigger issue was that Optane made the most sense when software treated storage and memory as one tier, and almost nobody was going to rewrite kernels, DBs, and apps for a product that cost more than flash and solved pain most buyers barely felt.

I don't think that would be my main complaint. Sticking optane in a dimm was just awkward as hell. You now have different bits of memory with very different characteristics, & you lose a ton of bandwidth.

If CXL was around at the time it would have been such a nice fit, allowing for much lower latency access.

It also seems like in spite of the bad fit, there were enough regular options drives, and they were indeed pretty incredible. Good endurance, reasonable price (and cheap as dirt if you consider that endurance/lifecycle cost!), some just fantastic performance figures. My conclusion is that alas there just aren't many people in the world who are serious about storage performance.