On the contrary, the criticism comes from having a good understanding of how this unit plays out in practice. Before the last patch the TK was universally seen as bottom tier UU and no one raised an eyebrow at their slight speed increase nor has any one remarked what a great unit they are now. The unit has a small niche, slightly larger than before but still rarely the best unit-choice for the Teutons. That may be fine for you but some of us would like to have a more frequent use of the unit.
Having a PA of 3 does not make a unit an uncounterable bulletsponge, this is just ridiculous hyperbole. Being slow, expensive and weak to arrows is a combination that does not work in this game.
Now I understand I am discussing with 2k ELO players who have a perfect game-understanding here, but let me remind you that Viper put the TK in the lowest tier (not counting flaming camel/missionary/elephant archer tier) and that was post-buff.