Fair enough. Sounds like you're saying that automatic buffer management algorithms don't work well because modern links often have variable bandwidth. Thus better algorithms need to be devised.
It is striking that many end users are told what bandwidth they achieve (numbers in browser download, file copy windows), but not link latency. Perhaps that has given ISPs an incentive to optimize for bandwidth (i.e. FastStart, or jack up buffer sizes) and not care about latency because it's hard to measure.
And if AQM/ECN requires all users of a link to turn it on, then adoption will be difficult. Tasks that want maximal bandwidth and don't care about latency (like browser downloads) have no incentive to use it.
Someone needs to write a mobile app that forces packet drops after it detects congestion and speeds up the browser experience. You do that and users will be clamoring for AQM.