While this is true, you must remember that the way that tau fight is very different to te imperiums tactics. While a hammerhead may be te direct equivalent of a leman russ in a straight-out fight, the leman russ was designed for staying power, while the hammerhead is designed with the tau philosophy in mind, which is all about guerilla tactics and it and run, rather than the "throw more men at it" tactics of the guard.
While I agree with you, I would still question that philosophy on open fields with my armored spearheads. Leman Russ have its own strengths against hammerhead that makes him more useful on average. While specialisation is no doubt useful, I doubt that it's ultimately wise for the Tau. They just simply are too small to be able to muster proper respond against forces who are hard counter for mobility and massive firepower from ambushes that Tau likes to use. For example: we have seen how Tau performed poorly versus Tyranids and Dark eldar who naturally negates their strengths. Not even talking about battle grounds unfavorable to them or strategic objectives which can work against them....
About criticism relating chainswords: do not imagine classic wood-cutting chainsaw. These weapons contain quite advanced technologies and materials. They have far far better characteristics than today's chainsaws and that's more, they are being wielded by far stronger users than your average puny human.
