Support Chaos Knight

Indeed. In fact I was thinking alot about, how every type of boots actually provides some benefit, but in the end I decided to highlight the two "supporty" boots. Phase boots and power treads help you to hit people harder and consistently but CKs ultimate and his chaos bolt are so expensive, relative to his mana pool. I think mana boots or tranquils+soul ring are necessary to provide the team with CKs disables.
The +20 Movement speed talent should be enough to compensate for the missing phase active and a medallion or basilius are cheap and easily gained armor points.
To take on your examples: ES and Tusk have much cheaper spells and more int gain than CK (poor 1.2/level), maybe that is the reason aggressive boots are more viable on them. I always had severe mana problems on CK when playing with treads (I think I only built phase boots once).