The opinion you shared were a first-hour one for many Tau players (and more).
Missiles are not that silly: they don't need much energy so it allow the big gun to be fired at will with a (relatively) small powerplant. So you have a reliable secondary weapon array.
Battlesuit ankles and feet stability is poor, but Tau have antigrav technology, so the battlesuit torso are probably grav-suspended (see kung-fu movies stunts for the ease of movement it can allow, even for battlesuit that stride).
GW's Tau design is now more Battlesuit oriented after being much more about mobile brigades (few Battlesuit elites covering vehicle mounted infantry squads with tank support).
The Riptide "giant" battlesuit case was very discussed at the time it appeared (didn't recall the thread here). Then Stormsurge and Taun'ar make that move sillier (but other are fine with). I remember the first time I read in IA3 1st ed that a revered Warhound titan was brought down by a makeshift sniperplane rigged from a bomber and the biggest gun Tau can brought on battelfield. Neat, smart, efficient, what is all Tau were. Now we have been contaminated by Imperium hubris for big legged chickens with oversized guns.
Let's hope Forgeworld will brought much more love in vehicles (after all, we have a moving fortification, so let's hope mobile brigade)
(Shameless plug following Aj'Tau
post ...) I bought one Stormsurge myself only to create arms and cockpit cover
, inspired by LimpWeanie work here on ATT.