Regarding the bolded part, Q1, early Q2 of 2014, the situation with darksend was pretty basic. 10 DRKs inputs in threes, mixing while sending (and having to wait).

The "V2" / second version would be a huge upgrade. Now for V2 there were 2 options of ring sigs and premixing+multiple rounds+multiple denominations (not only 10 DRKs). V2 delivered a radical upgrade through the second way.

What was promised but has not yet been delivered: ip obfuscation* (there was talk about i2p in the masternode network IIRC) and more recently masternode blinding. IIRC masternode blinding coincided with some other wallet app and it would have to be rewritten or something - so the spec was kept stable.

*One could argue that there is TOR compatibility.